Continuity mistake: In the 40th Anniversary release of the complete original series, this episode opens with Scotty at the conn, making an extended log entry, wearing his third-season swept-back hairstyle, and it is very obvious that he is visually mouthing several completely different sentences than we hear in the audio. After the opening credits roll, we next see Scotty wearing his more typical relaxed hairstyle with slight bangs. It is apparent that, in remastering and editing this episode, they inserted footage of Scotty from another episode altogether. For whatever reason, it is a glaring mistake of both continuity and audio editing.
Continuity mistake: Just before Parmen starts mind-controlling Kirk, McCoy and Spock, he presents them with three gifts. Kirk receives a large, gold Greek shield, which the captain holds with both hands, in front of him, as the lengthy scene continues. In the wide shot, Kirk is holding the shield high up on his chest, completely obscuring his Federation insignia. In subsequent close-ups, Kirk is holding the shield down low, around waist-level, fully exposing his chest and insignia. Every time the camera cuts back to wide-shot, Kirk is again holding the shield up high on his chest.
This Side of Paradise - S1-E25
Continuity mistake: As Kirk sits on the deserted bridge, there is nothing out of the ordinary with him. After he sits at the helm position, the camera looks at him over the console, and there's suddenly a spore spewing plant to shoot him.
Suggested correction: The plant did not suddenly appear, it was there from earlier in the episode.
This Side of Paradise - S1-E25
Other mistake: After Spock is hit with the spores, he goes down on all fours in pain. As he writhes around, the skin tone of his ears is vastly different to his other makeup.
A Taste of Armageddon - S1-E24
Continuity mistake: The chamber the guards try to shove Fox in is open when Spock shoos everyone away. But it's closed when he goes to blast it.
A Taste of Armageddon - S1-E24
Continuity mistake: At the door, as Spock gives Yeoman Tamura her orders, his hands are in front of him. In the close up, they are suddenly by his sides.
Continuity mistake: The hilt of the blade Kirk holds against Tracy's throat is close to Tracy's jawbone in the close ups and further away in the long shots.
And the Children Shall Lead - S3-E4
Continuity mistake: When Gorgon the Angel is on the bridge with the children, the positions of the children are different depending if the shot is from the rear of the children or the front.
Revealing mistake: As the camera is close to Dr. Sevrin, the line of the bald skin wig is easily seen.
Revealing mistake: Kirk uses a sword to cleave a Roman guard during his escape from the TV studio, but there is no blood on it. Later, though, when Claudius stabs Merrick in the back, there is blood on the knife blade.
Revealing mistake: Kirk uses a submachine-gun to shoot the lock of the cell holding Spock and McCoy, but no bullet holes appear, nor is the lock damaged.
Revealing mistake: A Roman guard empties half a magazine of bullets from his submachine-gun into Flavius, but there are no bullet holes in his body, nor blood on the floor from the wounds inflicted by the bullets.
Visible crew/equipment: Set lights are reflected in Spock's tricorder screen before he closes the cover.
Let That Be Your Last Battlefield - S3-E15
Revealing mistake: As Kirk turns all the way around to look at the newly arrived Bele, the shadows of the stage wiring is easily spotted at the top of the screen.
The Enterprise Incident - S3-E2
Continuity mistake: When the guard opens the cell barrier, the light bars turn off, then slide back. As they come back out, they're already on, rather than the reverse of the opening procedure.
Continuity mistake: To open the secret doors, Seven tilts one of the pen holders down to the top of the desk. After he's gone, Ms. Lincoln comes in looking for him, and the pen is upright without it having been pulled back up, unless it was supposed to reset itself.
The Enterprise Incident - S3-E2
Other mistake: As the Romulan commander goes to answer the intercom, the switch she touches to open the link is already on, probably left that way from a previous take.
Other mistake: In the cells, the particular strip of metal Kirk pulls loose has rivets that are noticeably different than the rest, making it easier to pull loose.
A Piece of the Action - S2-E17
Continuity mistake: The pistol Kirk is pointing at the gangster changes elevation and angle as the scene cuts between the front of Kirk and over his shoulder.
A Piece of the Action - S2-E17
Continuity mistake: The scene outside shows a guard standing close to a sign on the wall that says, "Jo Jo Krako", but the next overhead shot shows the guard further away, and a railing between the sign and the guard that would have prevented anyone from getting close to it.
