Trivia: When this film was made, many of the original, Russian crew members involved in this historic incident were very upset about the submarine crew being portrayed as drunkards. Oddly enough, one of the promotional items given out at premieres and to executives was a silver K-19 vodka flask.
Trivia: The 'American' destroyer seen from far away in several shots is actually the decommissioned destroyer HMCS Terra Nova.
Trivia: In real life, the K-19 was never nick-named "The Widowmaker," and its cursed history was entirely fictional, fabricated for the film. After the fact of the nuclear meltdown, the Soviet military actually nick-named the K-19 "Hiroshima," alluding to the first city ever destroyed by a nuclear weapon.
Trivia: There was never a mutiny aboard the real "K-19" as depicted in the film. In real life, the captain ordered all firearms to be thrown overboard, to avoid a mutiny.
Answer: The movie is correct on this. The early Soviet ballistic missile subs like this one had the missile launcher in the sail, carrying 3 missiles. Missile tubes integrated into the hull, and the ability to fire while completely submerged, didn't come til later.