Other mistake: Near the beginning of the movie, at the same time the ship makes radar contact, the sub acquires a signal on its oscillator. The sub captain thinks it's a false echo due to the rough seas. He so advises the next man that comes on duty but tells him that if the signal appears to get any closer, "you will awaken me immediately." The captain isn't awakened until the "dive" alarm sounds after the men in the conning tower make visual contact with the ship. Wouldn't the oscillator signal closing in on the sub have warned them long before they made visual contact?
The Enemy Below (1957)
1 other mistake
Directed by: Dick Powell
Starring: Robert Mitchum, David Hedison, Theodore Bikel, Curd Jürgens
Character mistake: About half-way into the movie the Captain asks for a fathometer reading and is told 150 fathoms. He preforms a mental calculation and says that it is 310 meters and over a thousand feet. In fact, 150 fathoms is 275 meters or 900 feet (1 fathom = 6 feet = 1.83 meters). (00:57:15 - 00:57:40)
Captain Murrell: I have no idea what he is, what he thinks. I don't want to know the man I'm... trying to destroy.
Trivia: The number of the (fictional) USS Haynes is DE-181. This number was actually used for the USS Straub - an actual Cannon Class escort destroyer.