Factual error: The premise for this episode has a major flaw: the only things that could shift the Earth's orbit significantly are a near passage of or a collision with an astronomical body of sufficient size to alter the course of a body weighing 6.6 sextillion tons - the mass of the Earth. Either event would cause sufficient disturbances that cities would probably not be left standing, nor would there be anyone left to stay in or flee from them. While the events of the episode are mostly a dream, the revelation is that the earth is actually moving away from the sun, not towards it, so the mistake applies regardless.
Suggested correction: The Earth's orbit moves outward and away from the Sun about 1.5cm every year. Eventually though the Earth will lose orbital energy and spiral into the Sun. Norma and the rest of Earth exist in a time when the planet has moved away from the Sun.
Five Characters in Search of an Exit - S3-E14
Factual error: When all 5 prisoners stand on each other's shoulders with the ballerina on top, she still can't reach the edge of the cylinder. But when just the 4 men do the same thing and the major throws his rope over the edge, he is somehow far closer to the top than he should be. He ought to be the ballerina's height and then some away - but he isn't. (00:21:30)
Factual error: The lieutenant is wearing cavalry insignia, but he is in the infantry company.
Showdown with Rance McGrew - S3-E20
Factual error: Throughout this episode, the TV western supposedly being filmed lacks several essential elements. There are no clapboards to mark the scenes; the modern-day car is constantly in shot through the swinging doors; and the set is located inside the "real" saloon when it should be on a sound stage.
Factual error: Author Damon Knight was happy with Rod Serling's TV adaptation of his short story - except for the change that allowed the humans to translate the Kanamit language as though it were a code. Said Knight, "Without some sort of interplanetary Rosetta Stone, deciphering an unknown language would be impossible." (00:22:10)
Factual error: As well as the obvious problem with translating an unknown language as if it was a code, there is no chance that the word "serve" would have the same double meaning in English and Kanamit. It would be like the word "dope" and its French equivalent meaning "idiot" and "illegal drugs" in both languages.