Visible crew/equipment: When the man is hit in the face with a pie whilst having his picture taken, you can see a crew man's hand throw the pie directly in his face.
The Battle of the Century (1927)
1 visible crew/equipment mistake - chronological order
Directed by: Clyde Bruckman
Starring: Oliver Hardy, Stan Laurel, Jack Adams, Wilson Benge
Continuity mistake: When Oliver tries to put the banana into Stan's hand, he puts it into his own hand and you can see the banana is facing right, but in the next shot the banana is now facing left.