Revealing mistake: When Diamond is driving with Ted, his wife and their dog in his convertible, the rear-view mirror, which was there earlier, is missing. The shaky rear-screen projection makes it even more obvious that the car is a studio mock-up with the mirror removed to make the actors' faces more visible.
And Whose Little Baby Are You? - S4-E18
Revealing mistake: The $100 bills Diamond picks up from the table are very obviously not real. The stage money's rather frilly design pattern looks vaguely like some currency from the 19th Century, but it doesn't resemble anything in circulation in the 1950s. (00:06:30)