Tomorrow is Yesterday - S1-E20
Continuity mistake: When Kirk and Sulu enter the records room, they pick the lock. Later when they beam the officer back down, he enters the room without unlocking the door. The room should be locked since they beamed him down in the "past" erasing their having been on Earth and in the records room.
Tomorrow is Yesterday - S1-E20
Continuity mistake: When the plane is coming up to intercept the Enterprise, it's shown flying through thin clouds, yet when inside the cockpit, there are no clouds to be seen.
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.