Continuity mistake: When the Disco Volante separates to escape the cruisers firing on it, the "cocoon" is seen facing the pursuing ships stern-first. When the shot changes to show the gunners firing on the ships, the back half of the "cocoon" has turned completely around. The gunners are firing from the separated mid-section of the Volante, and the stern of the "cocoon" is now facing away from the cruisers, making it easy to see which parts of the scene were filmed live and which were done in the studio.
Continuity mistake: When the Leslie Special is rolled out to be presented to the Great Leslie the red carpet in the front view starts at the building alignment. The aerial shot as seen from Professor Fate shows a wide gap between the building alignment and the red carpet.
Continuity mistake: When the German colonel crash lands in the Channel, he first hangs directly under his upside-down plane before he has to let go, and the plane zooms in a straight line away from him. But as he resurfaces in the foreground, the plane comes in from the background's left before landing in the water.
Continuity mistake: In the scene near the end when the men are done dragging the plane, one of the men unhooks the dragging strap under the left wing. In the next shot, it shows the pilot standing on top of the wing with the strap still attached. When the men climb the ladder to board the plane, the strap is gone. (02:14:40 - 02:15:15)
Continuity mistake: When the train is taking water it is sitting on a far right spur line, but when it leaves it is on the main line.