Visible crew/equipment: Chapter1: Purple Death. When Queen Fria says: "You see my friends, Ming has captured my general Lupi," you can see the shadow of the camera.
Flash Gordon Conquers the Universe (1940)
1 visible crew/equipment mistake - chronological order
Directed by: Ford Beebe, Ray Taylor
Starring: Anne Gwynne, Charles Middleton, Buster Crabbe, Carol Hughes
Continuity mistake: Chapter 2: Freezing Torture. When Dale falls from the mountain, her pick stays on the top but she still has it in her hands in the next shot.