Revealing mistake: During the initial dive the hydroplane on the sail (conning tower) is pointing upwards. During a later dive the hydroplane is pointing downwards. Wouldn't one position cause the submarine to surface?
Revealing mistake: The submarine Seaview is pursued down the Marianas Trench by a United Nations submarine trying to destroy it. Seaview's sonar operator reports torpedoes approaching port side even though the pursuing sub is directly astern of and always has been astern of the Seaview.
Revealing mistake: Captain Crane to thwart the bad guy has to exit the sub using scuba gear and make his way to a missile silo and attach a magnetic primer to the missile to fire it. Just before he uses the exit a crewman attaches the primer to his belt on the right hand side. As he is pulling himself along by the handholds on the deck the primer is no longer on that side. As he arrives at the silo the primer appears in his left hand.