Continuity mistake: When Elaan visits engineering, the close-up shots of Scotty show a security guard wearing a black utility belt standing in the background. But the man is missing in all the full shots. (00:13:15)
Continuity mistake: As Kirk wipes a tear from Elaan's face, both cheeks are wet. A second later, both cheeks are dry.
Continuity mistake: After Marta's dance, Kirk and Spock are sitting an inch apart behind the table, then a foot apart, then an inch again and so forth every time the shot changes. (00:16:25)
Continuity mistake: As Garth brings in the chair and orders the governor's torture, the pedestal fruit bowl on the table in front of Kirk keeps moving back and forth in relation to him and to the wine pitcher. (00:22:40)
Continuity mistake: When Garth forces Kirk to kneel at his feet, Kirk's hands are extended palms down, then palms up, then palms down again as the camera angles change. (00:34:20)
Continuity mistake: When Scott orders Sulu to fire phasers to punch through the force field, the two phaser beams are diverging when they leave the ship, but converging somehow (space mirrors?) when they strike the planet. (00:41:20)
Continuity mistake: After Garth attempts to convince Mr Scott that he is Captain Kirk and to beam him up, while he is banging his fists on the floor in anger he transforms back into himself and the fly like ring on his finger breaks and slides out of shot. It's quite hard to see but it does. The next time we see Garth's hand his ring is intact yet he has not transformed himself again to repair it.
Continuity mistake: When Scotty thwarts Garth, disguised as Kirk, attempts to beam to the Enterprise using the Queen-to-Queen level three code, Kirk throws a tantrum and accidentally loosens one of his controls during his rant right before he turns back to Garth.
Suggested correction: How is that a mistake?
Let That Be Your Last Battlefield - S3-E15
Continuity mistake: The planet Cheron is blue the first two times we see it on the view screen, but when the Enterprise enters orbit, and every time we see it thereafter, the planet has mysteriously turned red. (00:44:05 - 00:46:00)
Continuity mistake: When Kirk beams down to the planet, he selects the front transporter pad next to the steps, and closest to the door. When he materialises in the replica transporter room, he is on the same pad. When the scene cuts to a view of the empty transporter room, Kirk is no longer on the front pad. The scene cuts again, and Kirk steps off the front pad to walk to the control panel. (00:00:30 - 00:01:30)
Continuity mistake: When Kirk splits up the landing party, he asks McCoy to further inspect the vegetation. In the two shot, McCoy isn't wearing his tricorder, but in close-up, it's there, strapped over his left shoulder. Cut back to the two shot, though, and it's gone again. (00:10:20)
Continuity mistake: When Losira appears to D'Amato, he looks up from his tricorder, startled. The shot then changes angles, and D'Amato looks up at her all over again. (00:11:55)
Continuity mistake: When Mr. Scott asks Watkins to check the bypass valve, Watkins is facing the engineering boards with both hands on the panel. When we cut to a different angle, however, he's suddenly jumped to a position facing Scott with only one hand on the panel. (00:18:35)
Continuity mistake: When Losira comes for Kirk, he's holding Sulu's tricorder with both hands. When the angle changes to include her, he has it in one hand with his right hand at his side. Cut back to a three shot of Sulu, Kirk and McCoy, and Kirk has the tricorder in both hands again. (00:36:55)
Continuity mistake: When Kirk intervenes to keep Losira from touching Sulu, she jumps back about two feet and stops. When the camera cuts to look at her, she's still moving, and is about ten feet from Kirk.
Continuity mistake: On Memory Alpha, the viewer beside the dead man in the purple jumpsuit keeps moving from his left side to his right and back again between shots. (00:09:10 - 00:10:10)
Continuity mistake: As Mira is speaking with the alien's voice, Spock is behind a console that has a piece of equipment attached to it. From behind Spock, the piece is to his left, but the close ups of Spock show him close to and directly in front of it.
Requiem for Methuselah - S3-E19
Continuity mistake: When looking at the view screen from the helm, there is a man sitting at the Conn position, but in the wide angle, there's a woman there.
Continuity mistake: The leather strap with which the Troglytes lasso Spock disappears and reappears repeatedly from around his waist and shoulders during the scuffle at the mine entrance. (00:04:30)
Continuity mistake: In "Amok Time" Spock described Vulcan mating rituals as "a thing no out-worlder may know" - here he goes on about them with Droxine at some length.