Continuity mistake: During the conversation between Hercule Poirot and Ariadne Oliver on the bench, the same people keep passing by them over and over. Watch when Tina Fey says "I'm the smartest person"; behind her, there's a woman in a red coat, carrying a dark handbag. She walks behind them in the next shot; seconds later, she says "Then afterwards" in another close-up, and the woman reappears in the same position as the first time.
Continuity mistake: Sitting on a bench in Campiello dei Miracoli, Ariadne Oliver shows Poirot a series of newspaper clippings about the mysterious medium Mrs. Reynolds. Tina Fey's thumb is placed in a different position on the page in the various shots.
