K-19: The WidowmakerGoofs
Boom mic visible
Reactor Officer Vadim Radtchenko says that the accident may trigger a "Thermonuclear" explosion. This is impossible because Thermonuclear explosion is a nuclear Fusion (fusing Hydrogen atoms into Helium and thus releasing energy) and obviously the nuclear reactor in the submarine is based on nuclear Fission (breaking Uranium atoms thus releasing energy).
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.
Incorrectly regarded as goofs
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. In fact, this is not a Sikorsky S-58T but is a UH-24 which is a variant of the S-58T. The S-58T is the Civilian designator for this bird. Also, the S-58T ended production in 1970. It first entered service in 1954 so therefore COULD have (and actually Would have) been the helicopter used to scout the K-19.
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. However this is based in Soviet Russia it cannot be assumed the submarine/boat is new at all. Also the Soviet Union was known for its lack of equipment and the re-use of materials.
When the submarine has broken through the ice, as well as in the other outdoor scenes, the sun is high in the sky. This close to the North Pole, that indicates that it occurs in summer. However, in the simultaneous scenes from the launching and from the High Command inside Russia, it's snowing, indicating winter. If it was winter, there would be constant darkness where the submarine operated.