The U.S. Navy and the submarine base at New London, Connecticut, had to approve the story to protect military secrets.
Two cast members in studio records/casting call lists did not appear or were not identifiable in the movie. These were (with their character names): Ronald Reagan (Paul) and Broderick Crawford (Mike). Reagan is billed 6th in Daily Variety's preview cast list, indicating he was in the preview print. In addition, his character is mentioned in the pressbook as pivotal and a friend of Ann since childhood. However, none of the reviews mention him or his character, in all likelyhood because he was cut from the final released print.