Charlton Heston was originally offered the role of Ferraday but turned it down, saying there was no characterization in the script. Gregory Peck was then offered the part and early adverts in Variety magazine carried mention of Peck's casting, together with Laurence Harvey as Jones.
Laurence Harvey was originally cast in Patrick McGoohan's role and early adverts in Variety magazine even listed him in the part.
Patrick McGoohan was filming his famous TV series The Prisoner at the time he appeared in this movie. In order to allow him to take time off from his TV series, the episode "Do Not Forsake Me Oh My Darling" was written in which McGoohan's character, Number Six, has his mind transferred into the body of another man. "The Girl Who Was Death" was also altered so that No 6 wore a Sherlock Holmes disguise, so that his double Frank Maher could film a lot of the scenes.
Average Shot Length (ASL) = 7 seconds
In the era before VCRs, Howard Hughes would call the Las Vegas TV station he owned and order them to run a particular movie. Hughes so loved this that it aired on his Las Vegas station over 100 times.
Ron Masak's film debut.
The submarine used in this movie was the USS Ronquil (SS-396). Her hull number was repainted to 509. The first nuclear powered United States Submarine was the USS Nautilus (SSN-571).
This film was originally shown in Cinerama venues. In order to put it into these theatres, MGM pulled 2001: A Space Odyssey while it was still having a successful run.
This was Rock Hudson's favourite film of his own.