Continuity: When the submarine is leaving the berth, and the two captains are on the tower, the nearby flag blows away from them in the close-up shots. In the long shots, the flag (and other smoke) blows the other direction.
Continuity: Close-ups on some control consoles show new paint over layers that have been severely chipped, not something one would find on a new boat.
Continuity: At the beginning of the movie, Vostrikov wears his wedding ring on his left hand. In later shots it is on his right hand as is customary with Russians.
Boom mic visible: In the graveyard scene, near the end of the film, the boom mike can be seen reflected in one of the character's hats.
Continuity: When the K-19 is preparing to leave her berth for the first time, the order "single up all lines" is given. This order means that one set of lines is removed, but the boat should remain secured to her berth with a 'single' set of lines. When the order is given, the crew removes both sets of lines, and the K-19 departs.
Anachronisms: When Radtchenko kisses his girlfriend goodbye he tries to catch what appears to be a Soviet GAZ-66 4x4 utility truck. The production of GAZ-66 did not start until 1966, 5 years after the events of the movie take place.
Anachronisms: The US Navy helicopter flying around the K-19 is a Sikorsky S-58T, which had its first flight on 19 August 1970, about 9 years after the incident had taken place.
Audio/visual unsynchronized: The sound the camera makes when the group shot of the crew is taken on the ice is that of a fixed shutter, but the camera being used (either a Leica or a Russian copy) would have had a focal-plane shutter.
Revealing mistakes: In the "fuel fire" on board, the gas jets actually fueling the fire can clearly be seen at the bottom of the frame.
Anachronisms: The film shown by the political officer shows the Civil Rights abuses committed in Birmingham in 1964, four year after the K-19 was launched.
Continuity: When Alexei Vostrikov arrives to the meeting with the admirals his rank up to this point is that of Captain Second Class. However, during the meeting he wears the shoulder insignia of a captain first class. in the next segment when he boards the K-19 he once again is a captain second class.
Revealing mistakes: The CGI helicopter that flies close over the two soviet submarines doesn't cause a wake on the ocean.
Factual errors: The worry that the reactor might explode is flawed. Uranium as used in reactors must contain U-235 and may contain U-238 but the design is wrong to cause an explosion. A critical mass of U-235 or plutonium must be formed almost instantly for an explosion, which can't happen in a reactor.
Errors made by characters (possibly deliberate errors by the filmmakers): Traditionally, vessels are christened by women, but K-19 was christened by a man.