Continuity mistake: Decker is leaning over the forward console between Sulu and the other man, with Spock at his left elbow. As he gives the order to veer off, he starts to turn to his right. As the angle changes, it appears that he was standing straight up the whole time.
The Immunity Syndrome - S2-E18
Continuity mistake: During the teaser, Lt. Kyle is wearing a red tunic, but when Spock returns to the bridge after his examination, Kyle is now wearing a gold tunic.
Continuity mistake: When Scotty awakens in the sick room after being attacked by Nomad, Nurse Chapel has her hands placed on him. In the next shot, when McCoy tells Scotty to take it easy, Nurse Chapel's hands are no longer on Scotty, and in the next shot, her hands are back on him.
Continuity mistake: When the security team is escorting Nomad back to the holding area, he goes his own way. One of the team then says, "Hey Nomad!" and begins to reach for his phaser. But in the next shot, he has already got his phaser out and trained on Nomad.
Continuity mistake: The Klingon is standing on a hillside above Maab, yet when he fires his phaser, the beam streaks upward. From that angle, he wouldn't have hit anything but sky. Nevertheless, the beam somehow re-angles itself downward so that it hits and kills Maab. (00:46:05)
Continuity mistake: Mr Checkov has a rather unfortunate hair styling during the beginning of his role in Season 2. In this episode his hair is normal until the end, where in between being given an order and carrying it out he somehow manages to go and have his hair professionally done and made all bouffant. (00:47:15)
Continuity mistake: Mr. Sulu's equipment comes up to aid him at red alert, yet shortly after it is gone. (00:39:00 - 00:40:00)
Continuity mistake: Throughout the entire episode the planet's sky is red, yet during the scenes where the clouds come and lightning strikes, it becomes obvious that they simply used stock footage of Earth's clouds, since the sky is blue. (00:11:50)
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".
Continuity mistake: As there were two screen used models of the Enterprise, when the ship is seen flipping from one universe to the other and back, the nacelles of the Imperial Enterprise have the solid red fronts with what appear to be antennae.
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)
Continuity mistake: After their life threatening surgery, Spock and Sarek somehow manage to switch beds between being in surgery and recovering. (00:45:00)
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.