Plot hole: During the first poker game of the film, Vinny (John Fiedler) picks up one of his poker hands and straightens the cards in such a way that everyone else at the table can see them. Since the other guys gripe about how much Vinny is winning, neither Fiedler nor director Gene Saks must've known that his cards were visible.
Plot hole: When Jim is shown what he has to pay for the damages Herbie did to Mr. Wu's shop he says he has no money. First off if he had no money how in the world was he able to put down any money on the red sports car he had just purchased that night? Secondly, what happened to the prize money from all the races he was winning from the previous few months?