Episode Trivia


When "good" Kirk and Spock step into the transporter to go to sick bay, there is slight jump in the frame before "evil" Kirk's blood-stained hand thrusts onto the screen - revealing the cut that allows William Shatner to be in two places at once.
Apparently, the transporter isn't just giving Kirk split-personality problems; when Spock goes to reunite Kirk's two halves, watch him as he engages the beam and you will see his head and upper body vibrating, as though he were going to split in two.
On the bridge, Navigator Farrell's uniform goes from bearing the Enterprise chest insignia when Spock leaves, to having none when evil Kirk arrives, yet in that same scene, the insignia is present again when Farrell turns around to face evil Kirk.
When the evil Kirk makes the good Kirk drop his phaser during their fight, it falls behind evil Kirk. He then just bends down and picks it up, without having to back up or turn around to find it.
After trapping "evil" Kirk on the bridge, Shatner's double's hair is darker with obvious amounts of gray.
Evil Kirk's phaser changes between cuts in the shoot-out in Engineering
When Kirk confronts the evil Kirk on the bridge, the viewscreen is off in one scene and then on again in another and then off again.
Sulu fires his phaser at a rock to heat it up - he holds his hand still but the beam moves widely back and forth over the rock.
In the opening scene with Kirk and Sulu, the film is spliced in backward - their hair is parted on the wrong side. Also no one in the landing party has insignia. Presumably the director "flipped" the camera and tried to cover
When Captain Kirk is on Alfa-117, his shirt is missing the Enterprise insignia, but when Scotty escorts him to the sick-bay, the insignia magically appears. Not only that, but it also magically appears on the Evil Kirk's shirt as well. Later, when the Evil Kirk arrives on the bridge and orders the ship to break orbit, Mr. Farrell's shirt is missing the insignia, only to magically appear when the camera gets the reverse angle of Farrell.
The Evil Kirk steals a Type-2 phaser from Wilson. When he encounters the Good Kirk in engineering, he is holding a Type-1 phaser. However, when the camera cuts to a close-up of the weapon, it is back to being a Type-2 phaser. When the scene resumes, it's back to a Type-1.
Spock records a log entry as the "second officer". It appears they got "first officer" confused with "second in command".