The Gamesters of Triskelion - S2-E16
Continuity mistake: As Kirk gets up from the ground on Triskelion, his communicator is open. When he goes to use it, it's closed and he opens it.
Continuity mistake: The background of the cell does not jibe with the positions of Kirk and Cloud William as they fight - where Kirk and Cloud William should have either the cell's bars or the exposed brick wall behind them, there are shots of the opposite wall behind them instead, which is a plastered rock facing.
Revealing mistake: When Mr Hengist goes on the rampage in the hearing room, you can see that the actor playing Hengist is an obvious stunt double wearing a bald cap, whereas John Fiedler has hair on the back and sides.
Continuity mistake: As Nomad first hears Uhura's singing, it extends antennae and leaves the room. After a quick cut scene, as it turns in the corridor the antennae is retracted, then out again on the bridge.
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.
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.
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.
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.
A Piece of the Action - S2-E17
Continuity mistake: When Krako's men are in the gun battle with Bela's men, the Enterprise stuns them with its phasers. The number of bodies and their positions change after the men are stunned.
Continuity mistake: In the reception room, Amanda's glass goes from 1/4 filled after McCoy poured more, to over 3/4 full without his adding more.
Continuity mistake: After landing on the planet, the interior walls of the shuttle craft or well-lit, and light green in color. As Kirk and party exit, the interior is seen to be dark and gray.
Continuity mistake: In Norman's chamber, the medallions on Alice 3 and 11 go from blinking to steady, to totally off and back to blinking through the scene.
A Piece of the Action - S2-E17
Continuity mistake: After Kirk proposes a deal at the end, Oxmyx agrees and points towards the others behind him with his left hand. A second later, he's facing toward the camera with his right hand pointing.
Continuity mistake: When Kirk gives the order to Scott for transport, Spock lies in a diagonal position with the yellow spores on his chest with McCoy kneeling by him. After the cut to Scott on the bridge, Spock is lying with his head towards the camera, his chest is clean, and McCoy standing about six feet to Kirk's right. All much too quickly to be normal.
Answer: Kirk was getting his physical and Dr. McCoy probably turned off communications, because if he hadn't, Kirk would have left and headed straight for the bridge, leaving McCoy irritated.