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?