The Return of the Archons - S1-E22
Visible crew/equipment: After Scotty tells Kirk that the shields are unable to deflect the heat beams, the piercing soundwaves knock everyone out, and when Kirk awakens in the cell he tries to wake Spock, then the shadow of the camera is visible on the pillar as it follows Kirk. (00:25:55)
Visible crew/equipment: When the Metron returns Kirk to the Enterprise he reappears on the bridge, and the actors' chalk marks are visible on the floor where Kirk and crew stand. (00:47:20)
Continuity mistake: When Kirk informs Galileo that all systems are clear for takeoff, in the shot from inside the shuttlebay as Galileo turns to launch, the shuttlecraft Columbus is also in the hangar deck, but when Galileo exits Enterprise the Columbus is gone in the exterior shot. (00:01:45)
The Corbomite Maneuver - S1-E11
Visible crew/equipment: After the Fesarius destroys the recorder marker, when Balok declares that Enterprise must also be destroyed, in the next wide shot two tape marks are visible on the floor, one in front of Kirk's feet and another near Bailey. (00:21:50)
Where No Man Has Gone Before - S1-E4
Visible crew/equipment: While Kirk is armed with a phaser rifle he quietly moves closer to Gary and Dr. Dehner, but when Gary senses the "foolish man" he causes a boulder to roll past Kirk, and the arm of a crew member is visible behind the boulder pushing it forward. (00:39:40)
Where No Man Has Gone Before - S1-E4
Visible crew/equipment: While Kirk, Spock, and Dr. Dehner are with Gary in sickbay, when Gary makes threatening remarks and gets out of his bed, the shadow of the moving boom mic is visible on the wall at the left side of the screen. (00:28:55)
Continuity mistake: When Kirk confronts Spock in his quarters, Kirk asks if it's something only his planet can do for him, then Kirk uses his left hand to grab hold of Spock's arm as he drops the stylus, but in the closeup it's Kirk's right hand holding Spock's arm up, and that stylus is also back in Spock's raised hand. (00:12:25)
Visible crew/equipment: After Kirk and Spock place Hengist on the transporter platform to beam out, when McCoy and Scotty join them two white tape marks are visible on the floor. McCoy stands at one tape mark before Kirk begins to describe beaming it out into open space, and Scotty stands at the other tape mark as Kirk realises he'll be going alone to the cafe.
Visible crew/equipment: During Scotty's testimony, when Hengist agrees to the psycho-tricorder analysis of Scotty's memory Kirk tells Scotty he can step down, and the white tape mark is visible on the floor where Kirk stands. (00:28:20)
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)
The Gamesters of Triskelion - S2-E16
Continuity mistake: When Kirk, Uhura, and Chekov enter the transporter room Kirk is wearing his usual boots with heels, but while they're on Triskelion during some scenes Kirk's boots change to boots with flat rubber soles.
The Gamesters of Triskelion - S2-E16
Continuity mistake: During the final match, while Kirk fights the lone Andorian thrall two things to notice. Kirk's collar of obedience opens up and drops between the two opponents, then when Kirk lifts and flips the Andorian thrall the back of Kirk's black pants are split open in the wide shot. Both the collar and pants are intact in following shots. (00:45:25)
The Gamesters of Triskelion - S2-E16
Visible crew/equipment: When Kirk, Uhura, and Chekov are shown their quarters all the doors open, and when the trio try to escape they are shocked by their collars, then as the camera turns toward Chekov lying on the floor a production case (#4) is visible at the left side of the screen. (00:08:50)
Continuity mistake: After Maab gives Eleen back her life and forfeits his own life, when Keel throws the kleegat and hits Kras he drops the phaser in the closeup, but in the next long shot the phaser is back up in the Klingon's (stuntman) right hand. (00:45:50)
Visible crew/equipment: When Kirk regains consciousness in sickbay he asks McCoy about Sarek, and as the camera turns we see the white tape mark on the floor in front of Amanda's feet. (00:35:20)
Visible crew/equipment: While Spock and McCoy are discussing the dangers of the experimental drug, when McCoy tells Spock that he can't sanction it, the two white tape marks are visible on the floor. (00:26:30)
Visible crew/equipment: While Sarek is lying in sickbay, McCoy, Spock, and Kirk discuss the open heart procedure, and when Christine walks over to stand beside Sarek, the white tape mark is visible on the floor where she stands. (00:24:20)
Visible crew/equipment: When Kirk walks into the brig Spock tells him that Nomad has almost human stubbornness, and that its screens are still up, then just as Kirk moves closer to Nomad the shadow of the moving boom mic is visible at the top, left side of the screen. (00:28:15)
The Trouble With Tribbles - S2-E15
Visible crew/equipment: After Mr. Baris takes Darvin into custody and leaves the room, when Kirk walks over to Captain Koloth three white tape marks are visible on the floor. (00:45:10)
Let That Be Your Last Battlefield - S3-E15
Other mistake: At the end of the episode, as Lokai is running through the ship, his hands are empty. However, in one closeup shot he is holding onto a rope with his left hand. The rope is gone in the following shot. Presumably this rope was used to tether him to the camera as he ran so that he could maintain distance from the camera.
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.