Upon reading the film's script, the surviving crew members were so incensed that they sent an open letter to star Harrison Ford, producer/director Kathryn Bigelow and producers Christine Whitaker and Steven-Charles Jaffe, expressing their dismay. Among the less-than-credible details they objected to were profane language, the animosity between the two highest-ranking commanding officers, insubordination among the crew, drunk crew members, the attempted mutiny, the guns (which are kept under seal in a secret location) and the handcuffs (which were only used by and available to cops).
The blue glow inside the nuclear reactor is known as the Cherenkov effect. In order to simulate it, the crew poured 700 2-liter bottles of Canada Dry tonic water and illuminated the reactor with Ultraviolet light. The tonic water contains quinine, which emits a bluish glow in the presence of UV light.
According to Jacob Pitts during one scene the director of photography was having trouble getting Harrison Ford's eye line. When he asked Ford where he was looking Ford replied that he was looking into his soul. When the DP asked him where his soul was he replied "Under a pile of money."
The Juliette-class sub used for the filming had to be restored back to "sea-worthy" condition and then modified to make it resemble the original K-19, which was a Hotel-class sub. The modifications included a longer sail and lengthening of the sub by more than 100 feet.
Harrison Ford and Liam Neeson are both veterans of the Star Wars films. Ford played Han Solo in the original trilogy, while Neeson played Qui-Gon Jinn in Star Wars: Episode I - The Phantom Menace (1999). At one point during the filming process Neeson joked about his character getting to use a lightsaber while Ford bragged about his character surviving more than one film.
The Russian submarine used for filming was sold to the USS Saratoga Museum Foundation in Rhode Island for uses as an exhibit. It subsequently sank while docked in Providence during a severe rainstorm and was used by the US Navy as a salvage training exercise. After it was raised, it was no longer suitable as a museum and was sold for scrap metal.
The movie set of the sub was identical in size to the actual K-19 sub, thanks to the K-19 blueprints that were available to the producers. Since the sub's corridors were very narrow, the filming camera rolled along a rail system implemented on the ceiling. The rails were painted so they would blend with the sub's interiors.
The character of Executive Officer Mikhail Polenin is based on the historical Soviet Naval officer Vasili Arkhipov, who served as Deputy Commander and Executive Officer of K-19 during its 1961 nuclear accident. Arkhipov would later serve on the Soviet Submarine B-59 during the Cuban Missile Crisis, and reportedly refused to concur with the launch of a nuclear torpedo against an American destroyer, thus possible preventing the outbreak of World War III. Arkhipov would go on to hold several submarine command postings and was a submarine squadron commander before promotion to Rear Admiral in 1975. He was made a Vice Admiral in 1981, retiring a few years later, and died in 1998.
The actual K-19 was a Hotel-class ballistic missile submarine. The sub used in the movie is a modified Juliet-class guided missile submarine. The rescue sub in the film appears to be the SSK 73 RCN Onondaga, which was a Royal Canadian Navy submarine of the Ojibwa class (Improved British Oberon Class, or Super O's) which was launched on September 25, 1965 (four years after the K-19 incident).
The submarine that ties up along side K-19 and rescues the crew appears to be an Oberon Class (British Royal Navy class name, may differ elsewhere) diesel submarine with the sonar dome near the bow removed.
The meter used in the scene where the ships doctor is checking the radiation dosimeters by inserting them into a dosimeter reader is not actually a reader at all. It is a modified Hewlett Packard (now Agilent) HP3555A/B Transmission Level/Noise test set used by telephone and communications technicians. This actual meter was not developed by HP until several years after the K19 incident. The method for reading dosimeters at the time was to look through them (like you would a telescope) and read the progression of an indicator on a ruler like scale.
Both the rescue sub and the American destroyer were former Canadian warships. The American destroyer was actually an 'Improved Restigouche' Class Canadian destroyer escort which was decommissioned in the mid-'90s. This class did not have a flight deck for a helicopter. Both ships used were stationed in Halifax, Nova Scotia, home of the Canadian Atlantic fleet. Halifax was used in shots of the K-19 departing for sea. In the background of that shot, Canadian warships can be seen.