Visible crew/equipment: While Kirk and Spock are being chased, McCoy hears the gunfire so he stands up and walks away from the rock, then just as McCoy stops to use his communicator to contact Enterprise, the ground microphone is visible at the bottom, left corner of the screen. (00:02:30)
Continuity mistake: The gash on Kirk's right cheek disappears between the time he and McCoy fall asleep in the cave and when McCoy wakes up to find Kirk at Nona's side. (00:21:30 - 00:23:15)
Revealing mistake: Kirk jumps across the burning hot forge to hide from the people approaching him, only problem is that he actually touches the red hot coals with the palm of his hand. Somehow he managed to avoid serious burns. (00:31:15)
Continuity mistake: When Nona is trying to seduce Kirk, we see a close-up of him with nothing on his shoulders. Cut to a two-shot and suddenly Nona's arms are over his shoulders and around his neck. (00:41:00)
Revealing mistake: While Nona is struggling with her Villager attackers, the camera tilts just far enough to show, in the distance, a nice (if slightly smoggy) view of buildings, docks and boats in Santa Monica Harbor. (00:45:00)
Deliberate mistake: After one of the enemy villagers stabs Nona, during the ensuing fight when Kirk does a flying dropkick on a villager, this semi-closeup and the next wide shot are both flipped shots - the leather band is on Kirk's left upper arm, instead of his right. (00:46:15)
Continuity mistake: In the original version, the planet is the same as the one used in "Bread and Circuses", but when the Enterprise leaves orbit at the end, it is a totally different planet, as it is the one used in "Friday's Child".
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.