Feelings... Whoa, Whoa, Whoa - S11-E9
Factual error: Cliff is convinced his neighbor is Hitler, but if Adolf Hitler were alive in 1991-2, he'd be over a hundred, and surely someone as knowledgeable as Cliff would know that. And even if he doesn't, Frasier should know that as well and correct him.
Suggested correction: However, this is a character mistake, not a factual error. The show isn't misrepresenting an established fact; it's simply a character saying something that they're mistaken about. And Frasier simply can't be bothered correcting him.





