Revealing mistake: In the jail cell scene, when Kirk tears a strap from the bed, his left handcuff is open. It remains open for several seconds, while he tries to conceal it by moving his right hand to block the camera's view.
Continuity mistake: In a few episode we'll hear about "Hodgkin's Law of Parallel Development," but here Spock claims the odds of a planet developing similar to Earth's Nazi culture are "virtually impossible." Why was it so likely as to be easily accepted there, but impossible here?
Revealing mistake: After being put in the cell, when the camera is in a closeup of Spock, you can see the lines in the prosthetic ears, and can easily tell where the makeup is blended into his real ear.
Visible crew/equipment: After Melakon shoots at the curtained window and kills John Gill in the broadcast booth, Isak shoots Melakon, then when Eneg stops the soldier who points his gun at Isak, the shadow of the boom mic dips into view at the top, left side of the screen. (00:45:50)
Continuity mistake: The blood dripping from Isak's mouth changes sides.
Other mistake: In the cells, the particular strip of metal Kirk pulls loose has rivets that are noticeably different than the rest, making it easier to pull loose.
Revealing mistake: As Kirk and company exit through the tunnel, the seams of the wall sections are visible.
Answer: After causing Norman to overload, all of the other androids shut down. The same could be said for the androids on the Enterprise.