Revealing mistake: On the surface of Eden, Spock finds Adam dead under a fruit tree. But the corpse's fingers are still moving. (00:45:20)
Revealing mistake: Due to close-ups that were cut in backwards, Kirk appears in reverse, with his uniform insignia on the wrong side, twice in this episode: once in the corridor outside sickbay, and again near the shuttle craft on Eden. (00:18:15 - 00:46:55)
Revealing mistake: A re-used sickbay scene taken from an earlier episode causes Nurse Chapel to instantly revert to her old hairdo as the sound waves make her fall unconscious. (00:41:00)
Revealing mistake: As the camera is close to Dr. Sevrin, the line of the bald skin wig is easily seen.
Revealing mistake: As Scotty is cutting through the wall, the line where the burn is supposed to go is outlined on the inside of the wall.
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.