Visible crew/equipment: Just before Harold gets his hands caught in a window, a crew member can be seen gesturing his hands to keep raising the window cleaning gantry.
Other mistake: Harold Lloyd, aboard a cruise ship, looks over the railing. There is a shot of two sharks swimming in the water and another shot of several men rowing a kayak. However, the ship is just starting to pull away from the dock and Harold is on the side of the boat overlooking the dock. There is no way he could have seen sharks and rowers.
