Other mistake: When Superman pulls off the vault door and places it flat against the wall, it begins to fall back and he holds it back. He then leaves and the door is suddenly propped against the wall.
Adventures of Superman (1952)
1 other mistake in The Big Squeeze
Starring: George Reeves, Bill Kennedy, Jack Larson, John Hamilton
Revealing mistake: When the robot releases the balloon with the bomb attached, the wires used to pull the balloon up are visible as the balloon rises through the skylight.
Lois Lane: Eureka.