The Conscience of the King - S1-E14
Plot hole: After Kirk sees Leighton laying next to the rocks, he rushes over to examine him. He places one hand on Leighton's arm and the other on Leighton's waist and declares "It's Tom Leighton...he's dead." All this without the use of a medical tricorder or even the experienced opinion of the ship's doctor to confirm what Kirk is seeing. (00:10:46)
Other mistake: The only way to beam up to the ship is to repeat the chess counter move after ASKING to be beamed aboard. After the two Captain Kirks fight ends with Spock stunning Garth with the phaser, Spock contacts the Enterprise. After saying "Spock to Enterprise, and hearing Scotty say back to him "Scott here", Scotty says" Queen to Queen's level 3" without Spock requesting to be beamed aboard or even waiting to see what Spock wanted in the first place. (00:46:56)
Other mistake: Stiles gives a countdown for impact to Kirk saying "estimate it will overtake us in two minutes, sir." After only 31 seconds, Sulu starts his own countdown, saying "5, 4, 3, 2, 1, impact." Only 55 seconds have passed from the time Stiles started his countdown to actual impact. Everything was shot in real time without scene changes. Being off the impact estimate time by over a minute doesn't sit well considering a Starship's advanced sensors. (00:29:27)
Continuity mistake: Kirk turns his head and displays a stunned look... a full second before the Gorn even starts to disappear. (00:45:47)
Revealing mistake: As Scotty is cutting through the wall, the line where the burn is supposed to go is outlined on the inside of the wall.
Continuity mistake: At the end, on the Bridge, when the warning marker explodes, Kirk's arm shifts position between shots.
Continuity mistake: When Scotty inhales the gas, the amount of smoke changes between shots.
The Man Trap - S1-E2
Other mistake: Sulu is asking Janice why people call inanimate objects "she"? Then gives an example. He says "Like, she's a fast ship." But the subtitles get this wrong and have him saying "Like, she's a bad ship". (00:23:30)
The Return of the Archons - S1-E22
Other mistake: After Sulu is "absorbed", he is beamed up to the ship. After materializing, his demeanor could be described as calm, gentle, meek and euphoric. After that scene, the captain's log quotes Kirk as saying "Mr. Sulu has returned, but in a highly agitated mental state." Was Kirk looking at a different Sulu than we were? A gentle, meek and euphoric condition incorrectly being touted as "highly agitated"? Time for Shore Leave. (00:01:28 - 00:03:53)
Revealing mistake: It would seem that with the incredible advanced knowledge and furnishings that have been bestowed upon the Imorg down below, the 'Teacher' should have at least provided them with adequate high tech structuring and not the ratty, torn and warped substandard sheet rock seen on the bottom of the walls in these two camera shots. Yep, they can remove and restore a brain but can't find a place to buy good quality plasterboard. (00:23:40 - 00:33:51)
Other mistake: While on Starbase 11, Kirk and McCoy watch Pike on a starbase desktop monitor as his light keeps blinking no. When Kirk is with Mendez in his office discussing the Talos IV top secret file, Piper watches Pike on the desktop monitor in the office. Then Spock uses the desktop monitor in his quarters to watch Kirk. All these consoles have the same dings and markings around their screens, which are also the same as other desktop monitors on Enterprise in the previous episode, The Corbomite Maneuver. (00:11:10)
The Corbomite Maneuver - S1-E11
Other mistake: When Kirk is in sickbay with McCoy he uses sickbay's desktop monitor to contact Spock on the bridge, then when Kirk is in his quarters he uses his own desktop monitor to contact Spock again. Both have the same paint dings and smudges around the console screens, revealing the same one was used during filming. (00:04:30 - 00:06:30)
Revealing mistake: After Kirk and party are captured by the police, a montage of scenes depicting the planet's buildings plays while the log entry is heard. One of the buildings shown, though hard to read, has the title "Massachusetts Institute of Technology" (M.I.T.) above the columns.
The Immunity Syndrome - S2-E18
Other mistake: As McCoy stands by the hangar deck doors, the plaque over the pressure controls has "hangar" misspelled. It says "hanger".
Other mistake: The time that Kirk winds up in doesn't look anything like the what he was viewing on the disk.
Suggested correction: The entire planet isn't going to look exactly like what he saw on the disk. The disk will show random scenes to give the viewer an idea, but we can't expect the whole planet to match that image.
Other mistake: When Norman goes to the second panel in Auxiliary Control, there is clicking when he turns his right hand, but there is no knob, just a blinking light.
Other mistake: When the Planet Killer hits the Enterprise, the ship lurches 45° to starboard, and the crew fall accordingly. However, the chairs, except for the communications station, stay in place.
The Empath - S3-E12
Plot hole: Spock calculates that it will take 72 hours for the solar flare to pass, and Kirk orders the Enterprise out of the area. 3 days is a long time to go without food or water, and as the station is deserted as far as they know, there'd be no way to supply themselves, but the Enterprise leaves without a second thought.
Plot hole: Commodore Decker takes over command of the enterprise but Spock says if McCoy can certify him incompetent (which he obviously is) he can be relieved of command. McCoy says he will certify him now, so why doesn't he? In other episodes it has been stated that McCoy can order anybody regardless of rank to an examination to see if they are physically or mentally fit.
