Revealing mistake: When the dummy plane is shot out of the sky by the fighter pilot, a piece of the plane shoots off into the top left of the screen and bounces off the sky background. (00:23:05)
Revealing mistake: While the Seaview rocks violently back and forth from the concussion of the under water explosion, the pencils, folders, papers, etc., on the navigation table do not move.
Revealing mistake: At the very beginning of the episode, we see a hydrocharge being fired which causes an explosion in the sea. Then just a few shots later, another hydrocharge is fired and we see the same explosion - this is due to footage of one explosion being used twice.