The Ladykillers (1955)

Revealing mistake: During the scene where the gang attempt to catch the parrot, One-Round gets his legs stuck in a chair and falls over, breaking the chair in the process. About a minute later Herbert Lom breaks the record and it cuts back to One-Round, and the exact same shot of him falling over is seen again.

Professor Marcus: One-Round, there is a wheelbarrow outside, could you fetch it? The Major has a train to catch.