The Ultimate Computer - S2-E24
Continuity mistake: During the scene with the ore freighter, there are four closeups of Spock while he's bent over the scope at his station, and in the background behind Spock we can see Kirk and others on the bridge are gone. It also occurs in the earlier scene during the encounter with the two starships. (00:24:00)
The Ultimate Computer - S2-E24
Continuity mistake: When Sulu is first reporting the M-5 movements, Kirk's hand alternates between being up at his temple and down by his mouth, too quickly to be real.
The Ultimate Computer - S2-E24
Continuity mistake: The doctor and Spock are facing each other, the camera angle changes and they are suddenly shoulder to shoulder. (00:26:50)
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.