*Mortimer Brewster's cousin "Teddy," who believes he is Theodore Roosevelt, was called "Jerry" in an early draft of the screenplay and believed he was Gerald Ford. The character was modified when an unknown executive reminded everyone Ford wouldn't become President for another 30 years.
*Raymond Massey, who plays the deranged Boris Karloff lookalike in the film, took his role in good humor, but at a cocktail party, he once punched out a man who told him he resembled Margaret Hamilton.
*Karloff himself was supposed to play Massey's part, one he created and was concurrently performing in on stage, but he declined by saying, "Compared to THEATER, films are CRAP." But he said it in a really gentlemanly way with his classy accent, so nobody minded.
*If you look closely about 50 minutes into the film, you can see a cardboard standee of Ted Danson near a windowsill.