Continuity mistake: Nick Smith comes back from a trip and almost gets hit by a truck pulling 2 trailers. He gets out of the parked car and is stumbling into the restaurant. The next shot, Nick comes through the door with a broken cigarette suddenly hanging out of his mouth. It wasn't in his mouth or his hands before. (00:26:00 - 00:27:00)
Revealing mistake: When Cora's lawyer comes to the diner to tell her that townspeople are talking about Frank and her living together, Frank is holding a serving tray with glasses on it. The tray is tilted at an impossible angle yet the glasses still stay on the tray.