• Kevin Costner was originally cast as Jack Ryan.

  • Klaus Maria Brandauer was originally cast as Marko Ramius, but broke his leg prior to filming. It was Brandauer who suggested his friend Sean Connery for the role, having known him since they appeared together in Never Say Never Again (1983).

  • $20,000 was spent on Sean Connery's hairpiece.

  • During filming, several of the actors portraying U.S.S. Dallas crewmen took a cruise on a real submarine. To train for his role as the Dallas' commander, Scott Glenn was installed as the "commander" of the real sub and gave orders to the crewmen as the real captain would.

  • The crew of the U.S.S. Dallas adopted the tagline "The Hunt Is On" as an unofficial ship's motto.

  • Director Trademark: [John McTiernan] Jack Ryan takes a teddy bear home with him at the end of the film. McClane has one at the start of Die Hard (1988) (it's the same bear).

  • When the movie was first released on VHS in 1991, the tapes were red.

  • Most of Gates McFadden's role as Cathy Ryan was deleted from the final print.

  • The scene where Jack Ryan was lowered onto the U.S.S. Dallas was filmed in the parking lot of the Mole Pier at Long Beach Naval Station on a beautiful sunny day. Editing made it look like it was the ocean.