an underrated episode that spooked me and scared me in the mental frame was Parallel.
An astronaut, Major Robert Gaines, is orbiting the Earth in his space capsule. Suddenly, his communication systems stop functioning and he blacks out, waking up on Earth with no memory of his return. He appears to be none the worse for his experiences and is released to the custody of his family.
However, inconsistencies quickly pop up. His daughter senses that he is not the same person. His house has a white picket fence that he's never seen, though his wife insists that it was there when they bought the house. Everyone calls him
Colonel (confirmed by the rank insignia on his uniform) when he knows he's a
Major, and he insists that the
President of the United States is
John F. Kennedy, a man of whom no one else has ever heard. Gaines concludes that he must have slipped into a
parallel universe and tries to return to his space capsule, but blacks out again before he can do so.
He immediately finds himself back in orbit and lands his craft safely. He is prepared to write the whole thing off as a nightmare, but controllers on the ground subsequently receive another transmission