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)Jean G
Continuity mistake: The Providers' representative colors on the game platform and the thralls' collars (all three colors are on Galt's collar) are red, yellow and blue. But when Kirk appears before them, the Providers themselves are red, yellow and green, and so is the gaming symbol inside their glass bubble. (00:40:00)Jean G
Continuity mistake: Kirk's arrow strikes the Klingon in the knee. But a few shots later, the shaft is protruding from his thigh, several inches above its original position. Still later, he's holding one hand to his calf just below the knee, which isn't where the arrow was either time. (00:43:40)Jean G
Continuity mistake: During the scene when the Klingon agent is exposed by the Tribbles, Kirk first holds the two furballs as if they had a handle on the underside (probably for the parts to make them wriggle). As he turns to Spock (the wide-angle shot), he holds the Tribbles cupped in his hands, his thumbs supporting their flanks. But as Kirk approaches Spock (close-up), he has them 'by the handle' again.
Plot hole: The ambassador and his aide beam down to the planet. This would not be possible because earlier on Scotty refused to lower the screens/shields until the Captain told him to do so. It had already been established in an earlier episode titled "Arena" that transporters don't work with screens up. (00:32:40)olohzika
Continuity mistake: When Spock shows the others the machine which must be put "in the proximity of the Companion", in the closeup Spock's left arm is up on the machine and we see the chair opposite Spock is empty. However, in the next shot Spock's right arm is up by the machine and Kirk is sitting in that chair. (00:22:10)Super Grover