Paramount Studios essentially rented a US submarine to be in the movie. The USS Houston (SSN 713) played the USS Dallas and the surface scenes were filmed off of Long Beach, CA and Port Angelas, WA. Two crewmembers off the Houston were actually given very small speaking parts in the movie.

The color schemes of the three main submarines are different, so the audience can differentiate between them. The Red October is blue, the USS Dallas is red, and Captain Tupolov's (Stellan Skarsgard) boat is green.

The Alfa-class submarine Konovaljov commanded by Captain Tupolev is named after Soviet Admiral Arkadij Konovaljov. In March 1945, he sunk the German luxury liner Goya in the Baltic Sea on its way to Kiel, killing 6220 East Prussian refugees out of 6385.

The US submarine used by Paramount Studios, during the filming, accidentally sunk a tugboat when getting into position to film a scene. One of the submarine's radio antennas snagged the tow cable between the tug and a barge and this pulled the tugboat underwater. One person died.

The bear that Jack Ryan brings home to his daughter is the exact same bear Bruce Willis brings to his son in Die Hard (both films were directed by John McTiernan).

Because of its role in this film, the crew of the real USS Dallas adopted "The Hunt Is On" as the ship's motto.

Notice that Sean Connery is wearing his wedding band on his right hand. Married couples in the U.S.S.R. wore their wedding bands on their right hands.

In early stages on the film, Kevin Costner was cast as Jack Ryan and Klaus Maria Brandauer was cast as Captain Marko Ramius.

The Oliver Hazard Perry Class frigate USS Reuben James (FFG-57) shown in the film is the actual Reuben James.

Sean Connery originally declined the part of Marko Ramius, thinking that the story took place after Gorbachev rose to power and began the policies of detente and perestroika. After he was faxed the note shown at the beginning of the film declaring the events take place before Gorbachev, he accepted the role.

'Heathrow' at the beginning of the film is actually Los Angeles International Airport; just with a neon sign (which doesn't exist at the real Heathrow), and shot at night to cover up the rest of it.

Sean Connery, co-star of the movie and something of a stud in all his movies, declined the opportunity to go for an actual ride in a submarine while Hunt for Red October was being filmed. The gossip around the subs used in the movie was that he was afraid of going underwater in a submarine.

The USS Reuben James that intercepts the Red October (when she surfaces to let the crew off) figures prominently in Tom Clancy's "Red Storm Rising".

Sean Connery joined the cast after turning down the role of The Player in Tom Stoppard's adaptation of his play "Rosencrantz and Guildenstern Are Dead." The role was eventually given to Richard Dreyfuss.

Sean Connery's Scottish accent as a Russian submarine captain was voted the "Worst Movie Accent of All Time."