Visual Bloopers
by Bernd Schneider and Jörg Hillebrand
Scene DiscontinuitiesIncorrect GraphicsMisplaced ItemsVisible EquipmentVisible Crew & Stunt DoublesActor Mistakes & Prop MalfunctionsPossible Bloopers
Here is a collection of small filming or editing mistakes of the Star Trek TV and movie productions. They were either not recognized in time or considered minor, so they were not reshot or edited out. We deliberately picked some lesser known or newly discovered bloopers. See also: Prop and Set Oddities for some goofs that seem to be missing here. Please take the following pictures with a grain of salt. It is not our intention to acknowledge bloopers as canon evidence of strange things happening in the universe.
Scene Discontinuities
Sulu's tableware transformation
In TOS: "The Man Trap", Yeoman Rand brings Sulu a tray with salt and pepper shakers, a plate with vegetables and a bowl with colorful cubes on a saucer (the saucer is the same size as the plate). When Crewman Green (actually the M-113 creature in disguise) enters the room and is fixated on the salt shaker, we can still see the bowl. But in the following close take of the tray, there is no bowl any more but a second, larger plate on which the cubes (apparently made of vegetables) are placed.
Kirk rips open his own shirt?
There is a continuity error in TOS: "Shore Leave" in Kirk's fight with Finnegan. In the wide shot of Kirk (stunt double) lying on the ground we can see his shirt still intact. In the following close shot of Kirk (Shatner), two seconds later and still in the same position, the shirt is torn without Finnegan having anything to do with it.
Another door opens
In TOS: "The Return of the Archons", the landing party seeks shelter in a building during the "Red Hour" on Beta III. They enter through a double door with window insets. A second later, as the door is seen from inside, the panel arrangement is different and there are no windows any more. This is obviously because the interior set is located in a studio and not on the 40 Acres backlot in Culver City where the exterior was filmed.
The soft spade
Just after Spock and Kirk have activated the subsonic transmitter to induce anger in the brainwashed crew in TOS: "This Side of Paradise", we see DeSalle and Sulu working on a field with spades. This is established in a close-up of a metal blade turning over soil. When the two get into a fight in the directly following wide shots, however, both spades are very clearly stunt props made completely of wood.
Spock out of control
In TOS: "Spock's Brain", the brainless Spock is famously remote-controlled so he can be part of the landing party. He wears a head gear and a belt for that purpose. In the close shot of Kirk and McCoy lying on the floor this belt is suddenly gone, only to reappear one second later.
Chekov's twin
In TOS: "The Tholian Web", Pavel Chekov freaks out on the bridge under the influence of interdimensional space. Spock stuns him with the nerve pinch and orders two security officers to take him to sickbay. We can see how the bridge turbolift door closes behind them. Spock and McCoy keep talking for about two minutes in front of the turbolift. Then Tholian Commander Loskene appears on the main viewer, and Chekov is back in his seat! Of course, this is due to the use of stock footage.
The walking dead
On Memory Alpha in TOS: "The Lights of Zetar", Scotty, Kirk, Spock and McCoy enter a room with dead personnel. Kirk stops in front of a man in a purple jumpsuit (who is sometimes believed to be a Tellarite), whose shoulders are resting on a desk. Likewise, an Andorian is stretched across a console in the foreground. There is a cut to Kirk's face, and the next thing we see is supposedly from his perspective. One again, we can see the man in purple, but his head is pointing in the opposite direction. Also, the monitor was moved from the left to the right. What's more, the Andorian is no longer behind the console but lying in front of it!
Some kind of "Mirror Universe"
In the era of celluloid it occasionally happened that the film was right-left reversed in the process of editing. We can see one reversed shot of Kirk in TOS: "The Omega Glory" towards the end of the episode. He appears in the correct orientation only a moment later. Even two mirrored Kirks can be seen in TOS: "The Way to Eden".
A reversed Enterprise appears in TOS: "The Gamesters of Triskelion". This naturally only occurs in the original episode, as all shots of the ship in the remastered version are CGI.
In one take of the saucer crash in "Generations" the registry is reversed. This was due to the camera used to film that angle being pointed at a mirror so the saucer hit it and not the camera. And indeed the saucer broke the mirror.
TOS uniform errors
Scene discontinuities are most obvious in the case of wrong uniforms and insignia. Captain Kirk enters the turbolift in his standard issue yellowish uniform, whereas he exits wearing the green wrap-around variant in TOS: "Charlie X". In TOS: "Mudd's Women", Dr. McCoy awaits the arrival of the guests in the transporter room in his blue standard uniform, but in just one take he is wearing the shiny blue medical tunic, with sickbay in the background. This is apparently stock footage. For some reason, Scotty can be seen with a wrong science patch (instead of engineering) in a couple of shots in TOS: "The Lights of Zetar".
In "Star Trek: The Motion Picture", toward the end of the movie, McCoy and Spock switch their uniform jackets in a split second, between two takes.
Parallel timeline uniform
This is clearly one of the most famous costume errors. In the final scene of TNG: "Yesterday's Enterprise", after history has been restored, Guinan is curious about Tasha Yar, whom she met in the parallel timeline. In Ten Forward, she asks Geordi to tell her about Tasha. Geordi, however, is still wearing the alternate timeline uniform with the high collar.
DS9 uniform errors
Major Kira must have dressed in a hurry, as her communicator is upside down in DS9: "The Maquis, Part II". We can see how the O'Brien clone pulls his communicator off in DS9: "Whispers", and a rest of glue (or a Velcro fastener) is still visible on the uniform, which shouldn't be there for all we know.
In DS9: "Rules of Engagement" it seems that Captain Sisko has been demoted to commander in one shot, as there are only three pips on his dress uniform. In DS9: "Rapture", Captain Sisko (who appears with the gray vest most of the time in this episode) has misplaced the communicator in the gray shoulder part of his uniform jacket in every scene he is wearing it.
The Lt. JG rank pips on Ezri's uniform are reversed in some shots in DS9: "It's Only a Paper Moon". In DS9: "Penumbra", she even gets temporarily promoted to full lieutenant while she is on the runabout searching for Worf.
Gillian's two cars
In "Star Trek: The Voyage Home", the appearance of Gillian's pick-up truck, a 1974 Chevrolet, keeps changing all the time in the movie. There appear to be two distinct cars: #1 is used for the location shots in San Francisco (Presidio area) and Monterey (Cetacean Institute), #2 for the shots at the location that stands in for the Golden Gate Park on two occasions. The most obvious difference is the radiator grille. Also, details such as the placement of the bumper sticker are not the same on the two cars. Even the very same car #2 in the Golden Gate Park seems to change between its two appearances. The second time the lines on the fender and the door are far less pronounced.
Quick turning maneuver
In TNG: "Peak Performance", Worf's ship model is seen facing left (rudder on the right) in the wide shot, also still after Riker has entered. Only a few seconds later, when Worf wipes the model from the table and we can see it up close, however, it has changed direction, now facing right.
Someone else broke your ships
Speaking of broken ship models, in "Star Trek: First Contact" Picard famously smashes the glass showcase with the golden starship models with a phaser rifle. We can see that while he spreads shards all over the place, he doesn't damage any of the models. The Enterprise-D has a heavy list but is fully intact. But barely a second later later, after a cut to Lily's face, the Enterprise-C and -D are both broken. The saucer of the C has fallen off. The saucer of the D is still dangling but the model consists of four pieces now, of which Lily picks up a nacelle a minute later, when Picard has composed himself. Someone obviously had to make the damage retroactively fit with Lily's line "You broke your little ships".
Broken link fixed for "Broken Link"
In DS9: "For the Cause" the left solar panel of Sisko's ISS model, which is visible in all other episodes, is missing. It seems someone knocked off the panel and it was overlooked or there was no time fixing it. Anyway, prior to "Broken Link" the panel was repaired.
Uncovered label
During the battle simulation in "Star Trek II", the symbol on the starboard turbolift door of the simulator room is covered with something that looks like a reflective film. The reflection makes the logo almost unrecognizable. Most likely the transfer tape of the turbolift symbol sticker was not peeled off in time. The "A" above the turbolift logo, on the other hand, is the way we would expect it: not reflective and hence clearly visible. We can see the so covered logo a few times from slightly different camera positions behind Saavik. When the simulation is over and Admiral Kirk enters the room, the film is suddenly gone and the turbolift logo looks just like the "A". Someone must have spotted and removed the disturbing reflection in the meantime (provided that the scene was filmed about in the same order that it is shown, which is plausible in light of the mess created in the course of the battle).
Bashir and the fading label
In DS9: "Prophet Motive" O'Brien and Bashir play darts for the first time, then still in a cargo bay. The cargo container just behind them has a blazing pink label. But suddenly, in just one take of the scene, for a few seconds, the color switches to a pale, almost gray color. There is no plausible explanation for this obvious digital manipulation, with pink being the original color because the surrounding pixels of the gray label look blurry. Perhaps someone decided during the post-processing that the pink was too obtrusive. But why wasn't the whole scene changed accordingly? Moreover, several other labels in the same room are equally colorful. The letters on the label read "TransWormhole freight", and they are better recognizable on the gray version. In case someone had tried to obscure the letters by taking away the color, he would have achieved just the contrary.
Bashir gets a wrong picture
In DS9: "Melora" Julian Bashir picks up a photo of the Elaysian officer and her brother from a table. When the scene switches from the close view to the long shot, he is suddenly holding a completely different and larger picture. Only the frame seems to be still the same.
Bashir on silent feet
Although he was seen with black boots earlier in the same scene, Dr. Bashir wears white tennis shoes with his uniform in TNG: "Birthright I" as he walks away. Siddig El Fadil explained that this was done to reduce noise during filming.
Beverly's hairstyle secrets
Gates McFadden has thinner hair than Beverly Crusher. She is wearing wigs most of the time, if not permanently, during the seven seasons of TNG. In the third season Beverly Crusher sports a chin-length haircut, as it can be seen in TNG: "Booby Trap". Briefly later, in TNG: "The Enemy", she can be seen with long hair. But the long hairstyle lasts for just this one episode. In TNG: "The Price", just one week later, she has a shorter haircut again. Beverly will have long hair again as late as in the fifth season, such as in TNG: "Cause and Effect".
In the same vein, we can see in TNG: "When the Bough Breaks" that Beverly's fingernails are short, but in one close shot of their hands they are quite long. Most likely these belong to a stand-in and not to Gates McFadden. We need to wonder anyway how she could possibly operate a tricorder or a laser scalpel with such long nails...
Alien hairstyle secrets
In VOY: "Prophecy" Captain Kohlar initially appears with the slightly curly dark brown hair we know from most Klingons, be they male or female. When he comes aboard Voyager, Kohlar suddenly has a plain black Janet Jackson-style permanent wave. His hairstyle changes back and forth a couple of times during the episode. We can only hope that he is using gentle haircare products...
Most likely the perm version was filmed first, as all scenes with this hairstyle take place in the briefing room. Someone may have noticed that the black curls looked silly on him, and decided to switch to the traditional warrior-style wig. Only that it was ignored that the scenes with the two hairstyles would alternate in the final version of the episode.
But Kohlar is not the first Klingon who changes his hairstyle in the twinkling of an eye. Lieutenant Worf combs his hair straight down in the instant just prior to pushing the "fire" button in "The Best of Both Worlds II".
It is only fair that the Romulans know the secret of rapid restyling too, like Sela demonstrates between the two parts of TNG: "Redemption". Bang goes the Romulan bang.
Eventually it doesn't seem to be a question of advanced technology, however. In TNG: "Justice" the hairstyle of Livan, a member of the rather naive Edo species, changes in a matter of a few seconds as well when she is beamed up to the Enterprise. Suddenly dark natural hair grows out underneath the formerly dense blond perm bonnet. Or do we have to blame a misalignment of the Enterprise's transporter?
A tale of two Rikers
In ENT: "These Are The Voyages" we can spot two Rikers in once scene in Ten Forward. This is because stock footage from TNG: "Ménage à Troi" where Riker was already visible was digitally supplemented with a new Riker for the ENT series finale.
The time-traveling knife
In PIC: "Nepenthe", when Hugh looks around the corner, Narissa's Romulan throwing knife can already be seen in place, embedded in his neck - a few seconds before she throws it.
Starship mutations
Towards the end of TNG: "The Perfect Mate", in the first shot showing the Kriosian ship (before Picard and Briam enter the transporter room), stock footage of the USS Enterprise-D and the small Talarian observation craft from "Suddenly Human" is used. When the two ships part ways at the very end of the episode, this is stock footage from "Suddenly Human" again. But this time, the much larger Talarian warship is seen instead.
There is a separate article on this and other starships that change from one type to another during an episode, due to the use of incompatible stock footage: Starship Mutations.
Incorrect Graphics
Typos in credits
The typo "Scpipt supervisor - George A . Rutter" can be found in the end credits of several episodes of season 1 of TOS. "Star Trek: The Undiscovered Country" famously has an embarrassing misspelling in its end credits: "Uhuru".
Caution: decompressible wardrobe
The USS Enterprise hangar deck is misspelled "hanger deck" in TOS: "Journey to Babel".
The Wrath of Kahless
The Klingon logo appears the wrong way round on a screen in "Star Trek V".
New Zealand is gone!
When Picard shows Lily that they are in space in "Star Trek: First Contact", he points out what can be seen: "Australia, New Guinea, the Solomons." But it is more interesting what isn't visible: New Zealand! Well, this blooper has been "proven" and "debunked" time and again. The reason for the disagreement is that the view of the globe in the movie is not correct in the first place.
If we try to reconstruct Australia, New Guinea and New Caledonia with correct angles as Picard and Lily can see it, the majority of these land masses end up in the northern hemisphere from their perspective. There are additional distortions that can't be compensated for (at least not without distorting the globe itself). Anyway, even with all these inaccuracies we should be able to see the whole of New Zealand's North Island and a part of South Island, so this seems to confirm that it is a mistake./p>
Those who seek to debunk the blooper reconstruct the view differently. They turn Earth so the coast of Western Australia is at the according edge of the globe as seen in "First Contact". But now the land masses end up looking very different from Picard and Lily's perspective. For instance, New Caledonia is far "below" Cape York now, the northern tip of Queensland. And yes, New Zealand would indeed lie beyond the edge of the frame.
My own reconstruction is a compromise between the correct placement relative to the edge and the correct relative positions of the land masses. My judgment is that most of the North Island of New Zealand should be visible about half-way between Canberra and Lily's neck. We come to the same conclusion if we simply postulate that New Caledonia, Canberra and Auckland form an equilateral triangle, which is approximately the case if we look straight down on Earth in this region.
TNG on TNG
We can see a Star Trek TNG logo on an engineering display in TNG: "Identity Crisis".
This blooper was eliminated when the episode was remastered.
Ancient LCARS versions
In VOY: "Good Shepherd" we can see Mac pop-up menus and a mouse pointer on LCARS screens.
Mike Okuda: "That's a visual effects error. The logo on the screen in that frame is the 'slate' that I put at the beginning of the computer animation so that my colleagues in visual effects would know which shot it was to go with. Although they did a good job in compositing my animation into the filmed scene, they inadvertently included a little bit of the slate. It's really not that bad of a mistake, seeing as how few people have noticed it over the years."
A mouse pointer also appears on a screen on Enterprixe NX-01 in ENT: "Stratagem".
Some 20 years later, in PIC: "Maps and Legends", the blue 21st century interface is briefly visible before it makes way for the full-screen LCARS.
Simultaneous simulation?
The mirror writing "End Simulation" after the simulated destruction of Qo'noS in DIS: "Will You Take My Hand?" actually reads "End Simultation".
Vive la Républicique!
Besides the obvious misspelling of "République", there are several more errors on Renée Picard's French passport in PIC: "Fly Me to the Moon". It has her birth date listed American-style as "11 22 1996" (the US release date of "First Contact", directed by Jonathan Frakes). The issue date and expiration date, on the other hand, are correctly European-style. Curiously, the card reader incorrectly recognizes the birth date as "July 1st 1996". Also, the accents on "Préfecture" and "Béziers" are the wrong way round (grave instead of aigu). Furthermore, if there are accents on these two words (it would be an option to omit them on capital letters), they have to be on "Renée" and on "Châteauneuf" as well, which are the same font and size.
Misplaced phaser beam
While this list of bloopers is far from complete, we don't want to omit one of the most famous ones: the phaser beam from the torpedo launcher in "Darmok".
This clear error was corrected in the remastered episode by simply showing stock footage of the beam coming from the phaser strip.
Misplaced Items
Blue uniform?
A blue shirt or jacket is hanging over a a chair on the bridge in TOS: "Let That Be You Last Battlefield". We may say that someone decided to get rid of his or her uniform, but the blue is darker than that so it apparently belongs to someone of the production crew.
Who watches the watches?
Dr. Crusher's visible wrist watch in TNG: "Code of Honor" and once again in "Skin of Evil" is a typical blooper as it may occur during the filming. Basically there is no reason why people in the 24th century shouldn't wear (smart-)watches. But since we almost never see any of them, the most likely explanation is that Gates McFadden simply forgot to take it off prior to the shooting. Another wrist watch can be seen in DS9: "Progress". And Lieutenant Kelso wore one as early as in TOS: "Where No Man Has Gone Before".
Misplaced scripts
Someone obviously left an episode script on a cabinet in Dr. Crusher's sickbay in TNG: "Suddenly Human". The same happens in "Violations", "Ethics" and "Cost of Living" and some more TNG episodes.
In the Dixon Hill holographic scenario in TNG: "The Big Goodbye", a yellowish paper folder can be seen on the desk in the foreground. There is nothing on top of this folder. A few moments later, Data is seen leaving the office and the folder comes into sight again. Now, a sheet of a paper with two anachronistic color photographs (and a Post-it?) is lying on top of the folder. As nobody was in the room in those two minutes, the sheet of paper must have been left behind by a member of the production crew during filming.
Disposable bottle
A present-day plastic water bottle comes into sight behind the shelf in Phlox's sickbay in ENT: "The Breach".
Visible Equipment
Breaking the fourth wall
TV sets are no real rooms. They often lack a ceiling, and the side walls are not complete, depending on how far the camera is supposed to pan or zoom out. It happens occasionally that the set borders come into sight nonetheless. Well, usually it is just a minor nuisance and is often not even recognizable at the first glance.
For the remastering of TNG, visible set borders were sometimes eliminated through digital manipulation or through simple reframing, but in many cases they can still be noticed.
In VOY: "Basics II", we initially see Hogan in the cave entrance, shot on location. The following take from the perspective of the monster was filmed in the studio and shows a portion of the studio wall.
The only blatant one among our examples is ENT: "Bound". Here a whole panel of the rear wall of the bridge is missing, although it must have been clear to the director that it would be visible.
Black cardboard and similar items
In some early TNG episodes we can see that parts of the large displays on the rear end of the Enterprise-D bridge are covered with black cardboard. Our best guess is that the cardboard is supposed to avoid bothersome reflections. Obviously the lighting of the set was improved at a later date.
Guy Vardaman, who was a frequent stand-in performer in TNG, tells us the following about the cardboard trick: "Yes, the black cards were there to block the reflections of the lights and were hoped to be invisible to the viewer. There are also lines of black electrical tape and another trick used is to spray something with hairspray to dull it down when it is too shiny and would reflect crew, camera and lights.
The black cards went away because we got a new Director of Photography, Marvin Rush, replacing Ed Brown. Marvin lit the sets much more dynamically (less 'flat') and so he didn't have as much overall light. Also as film got better, technologically, it needed less light.
The hairspray trick was rarely used on Trek, but is used a lot in general production, especially on chrome trim on cars, etc. Mainly outdoors."
Not necessarily a cardboard sheet but definitely something black that doesn't belong there is visible on the bridge through the ready room's open door in TNG: "The Survivors".
Guy Vardaman on the "box" in "The Survivors": "Hey, that thing is a flag used to block light, usually mounted to a 'C-Stand.' So if they wanted to light Riker coming out of the ready room but not have a big shadow or beam of light coming out the door onto the bridge floor, they would block it with a flag like you are seeing."
In later TNG episodes, there was apparently still concern about reflective surfaces in the form of mirrors, as they could be found in the crew's bathrooms. When they were not needed for someone to look into, they were often frosted with hairspray or, apparently more often, covered with black cardboard.
Floor markings
In TOS: "Journey to Babel", floor markings are visible, as they were probably used to define the actors' positions. Another one is seen in TNG: "The Naked Now" in the observation lounge, after Geordi has been infected. There are markers in DS9: "Rules of Acquisition" (perhaps from a previously shot scene where Kira was speaking with the Nagus) and one for O'Brien's position on the upper level of the promenade deck in DS9: "Ferengi Love Songs".
Carpet patches
Carpet patches appear in many TNG episodes, often used to cover power cords leading to consoles or to the sickbay biobed. Likewise, in DS9: "Treachery, Faith and the Great River", we can see a differently colored piece of carpet, covering the hole for the cables of Sisko's missing desk.
The carpet patches were digitally removed in some TNG-R episodes such as on the bridge "Evolution". In "Time Squared", a carpet square next to the biobed was edited out for one shot but not for the following one.
A whole carpet roll, held together with duct tape, can be seen in "Star Trek: The Final Frontier".
Handbag? Sandbag!
No, it's not Riker's handbag that we can see in TNG: "The Child" (look at his feet). Actually, it is a sandbag, used in TV or movie production to secure a C stand (a tripod stand to mount lights on).
The bag on the floor is no longer visible in TNG-R as the shot has been reframed. The power connections under the captain's chair are visible, however.
Various visible equipment
A boom mic can be seen at the very left of the frame in TOS: "The Enemy Within". A piece of lighting equipment, probably a soft box, comes into sight in TOS: "Requiem for Methuselah".
The blooper in TOS: "The Enemy Within" was fixed for the remastered release by reframing the shot. The box, on the other hand, is still visible in TOS-R: "Requiem for Methuselah".
A microphone stand is visible when Riker enters a turbolift in TNG: "When the Bough Breaks". The same happens again in TNG: "Man of the People". There are several more TNG episodes with visible equipment.
Looking at TNG-R, sometimes the remastering removed the problem because the shot was reframed (such as in "Where Silence Has Lease") or digitally edited (such as in "The Masterpiece Society"); sometimes it created a new issue because previously invisible equipment comes into sight (such as in "Home Soil" or "The Child").
Finally, occasionally shadows or reflections reveal filming equipment.
In VOY: "Mortal Coil", we can see the reflection of the ceiling lights behind the Doctor and Seven as they treat Neelix with nanoprobes, but also some sort of moving cables, probably belonging to the camera or lighting.
Unidentified pole
In TOS: "This Side of Paradise", when Spock has just been struck by the spores, a pole comes into sight that shouldn't be there, and possibly the leg of a person who is standing next to it.
Bound to act
In TOS: "Let That Be Your Last Battlefield", Lokai is holding some sort of cord while running through the corridor. The reason for this may be that the actor is supposed to keep a certain distance to the camera.
When Kirk gets zapped by "God" in "Star Trek V", we can see the stunt wire that is used to yank him back.
Cabled rock
At the end of DS9: "For The Cause", when Ziyal and Garak are in the sauna and Garak goes to lay down on the rocks, you can see on the bottom right of the screen what looks like a hose (for the steam) or a cable (for the lighting) going to the island where they are laying from off-screen.
Visible Crew & Stunt Doubles
Give me a hand!
In TOS: "Where No Man Has Gone Before", the hand that pushes down a boulder can be briefly seen. We can see a finger of the hand that makes the wipers of Sulu's helicopter move in "Star Trek IV". On still another occasion, after the shuttle crash in "Star Trek V", when Kirk is fighting with Sybok, the two should initially be alone in the shuttlebay. But we can see an arm, obviously of someone who assisted the Sybok stunt double in hurling around the Kirk stunt double.
Mirror image
The face of boom operator Bill Gocke can be seen mirrored in a Romulan (plexi)glass sculpture in TNG: "Unification II".
The well-known blooper was removed in remastered episode.
I'm the invisible man!
In the original version of TNG: "Birthright I", makeup artist June Abston Haymore can famously be seen sitting on the ground in front of an orange door in Data's dream sequence.
While she is still briefly visible in the remastered version of the episode at the beginning of the sequence, she was digitally removed from the more obvious shot a few frames later.
As Sisko digs up the Orb of the Emissary in DS9: "Shadows and Symbols", we can see the head of someone walking behind the rocks in the background. In VOY: "Flesh and Blood I" a crew member with a t-shirt can be seen as Tuvok is walking towards the Hirogen technician.
Double trouble
TOS: "Court Martial" and "Space Seed" are two examples where Kirk is clearly not being played by Shatner in stunt sequences.
A very obvious appearance of stunt doubles can be witnessed in TNG: "Conspiracy". Riker and Quinn suddenly mutate as their fight starts. Riker's face changes, and Quinn's hair now grows down to his collar - "Vitamins: They do wonders for the hairline!". :-D
In TNG: "The High Ground" Patrick Stewart's stunt double John Nowak is clearly recognizable when he strikes an Ansata terrorist. Nowak reappears in "Man of the People".
In the Blu-ray version, we can recognize that the man on the carriage in TNG: "Time's Arrow II" is not Brent Spiner. His regular stunt double Brian J. Williams can be seen in various episodes, such as in "Descent I".
When Riker gets a blow to his stomach in TNG: "Starship Mine", he is clearly played by a stunt double. Stunt doubles are also recognizable as such during Picard's fight with Soran in "Star Trek Generations".
Actor Mistakes & Prop Malfunctions
Damaged walls
Charlie Evans hurls Spock and Kirk against a wall in Janice Rand's quarters, which leaves visible damage in the wall. In TOS: "Day of the Dove", on the other hand, Chekov harasses a Klingon woman and Walter Koenig apparently keeps brown make-up on his hands. When Kirk pulls him away and he falls with his back against a wall, his hands leave brown stains.
Andorian Pinkskin
Andorians are supposed to be blue all over. But this one exhibits some flesh-colored skin in TOS: "The Gamesters of Triskelion".
Ripping event
Captain Kirk is notorious for winding up with a ripped shirt in his countless brawls. In TOS: "The Savage Curtain" a different piece of clothing is ruined, albeit definitely not on purpose. The same apparently happened to the stunt double in "The Gamesters of Triskelion", whom we can see in just one short take in the final fight sequence.
Tarred phaser
After Riker has been drawn into the tar pit in TNG: "Skin of Evil", Geordi, Data and Crusher rush to help him. When they stop at the edge of the tar pit, Geordi's phaser drops straight into the tar. While this is no problem in the story, it almost definitely didn't happen on purpose.
Geordi's eyes
Also in TNG: "Skin of Evil", Armus wipes away Geordi's VISOR, exposing his eyes. In the original episode, the eyes were probably whitened in post production.
In TNG-R, on the other hand, it was forgotten to digitally modify Geordi's eyes accordingly.
20th century tech exposed
In TNG: "Lonely Among Us", Beverly sits down with a large PADD. The prop appears to have a battery slot, which opens during the scene, revealing cables inside.
Upside-down tricorder
Dr. Marr may be a mad scientist, but not so confused that we would expect her to hold a tricorder upside down like she did in TNG: "Silicon Avatar". We may tend to forgive Quark who made the same mistake when he defused the warhead in DS9: "Starship Down".
Don't break your neck!
When Dukat rests his head on a rock in DS9: "Indiscretion", we can see how his prosthetic neck cord detaches.
Don't shake too hard!
In DS9: "Return to Grace" Kira Nerys explains to Ziyal the operation principle of a Cardassian and a Starfleet rifle. Illustrating the "fully autonomous recharge" of the Starfleet weapon, she opens and then visibly and audibly closes the lid of the power pack at the bottom. Two seconds later, when she demonstrates the gyro stabilization by shaking the rifle, the lid flips open again, causing a smile in Nana Visitor's face.
Don't shoot... yourself!
Burnham holds Lorca at gunpoint in DIS: "What's Past is Prologue". But the nozzle points in her direction! In the following close take of the same scene the direction is correct. This apparently didn't go unnoticed, and a "click" sound was inserted between the two takes to support the impression that Burnham quickly flipped the phaser around.
Cross-hatched
Sometimes the limits of the set become visible in the heat of the action. In "Star Trek IV", when the hatch on the Bird-of-Prey is blown, we can see right out it and into... a wall, apparently with a ladder.
In DS9: "Broken Link" Garak attempts to fire the Defiant's weapons on the Founders' homeworld. When Worf catches him red-handed, the two fight inside a Jefferies tube. In the course of their struggle the hatch in the background falls off and we can glimpse behind the scenes.
I can reach any star
In VOY: "Investigations" Tom Paris grabs the frame of the Kazon shuttle windshield during a battle. It looks like there is no glass in the window and his hand is reaching out into space. The same already happened to "John Doe" in the observation lounge in TNG: "Transfigurations".
Possible Bloopers
11-"00"-1001
In TNG: "11001001" we see two Bynars enter the bridge from the starboard side - not from the observation lounge door seen behind them but from the corner where only the restroom is (supposedly) located. So just like two of them work as a unit, Bynars may have to visit the restroom in couples.
What's so funny, Number One?
In a scene which was not intended to be humorous in TNG: "Masks" we can see Riker with a wide grin on his face. Can it be that Jonathan Frakes was amused about Stewart holding what looks like a big phallic symbol? Like Kirk famously in TOS: "What are Little Girls Made of?"?
See Also
Prop and Set Oddities - inconsistent and otherwise unfitting props and sets
Starship Mutations - ships and shuttles whose type miraculously changes during an episode
Credits
Most HD screen caps from TrekCore or TrekCaps. The floor markings in TOS, the "Generations" bloopers and several other things were discovered by Michael Minnick, the microphone stand and Sisko's wrong communicator placement by Robb, the pole in "This Side of Paradise" by Guy Vardaman, the lighting equipment and discarded uniform in TOS by Jan Kockrow, the boom mic in TOS by Trek on the Tube, the visible equipment in "Mortal Coil" by João Paulo Cursino, more floor markings by Marcus, Rich, Walter Poulsen and LogicDeLuxe, Beverly's fingernails by Thomas, Crusher's watch in "Skin of Evil" by Josh Gilhen, the phaser in the tar pit by Claudius Göring, the sandbag on the bridge by Simon Turner, the cable in "For the Cause" by Walter Poulsen, the hand on the rock by Todd Kinkel, Dukat's "broken neck" by Max Pinton, Picard's "phallic symbol" by Thomas, the upside-down tricorder by Remy Chan (Chello) and by William Paul, the open phaser cell lid by Alexander Baier and Claudius, the turbolift sign by Chris, the walking head by wowbobwow and Rob Fini, the crew member with t-shirt by Dennis Verheijen and the water bottle by [email protected]. Some TOS bloopers are from the video Star Trek Goofs and Bloopers. Thanks to Wes Button for the hint about the transfer tape. Thanks to Dan, satre and Lee for their contributions!