Continuity mistake: After the fire in the captain's quarters everyone goes on deck for some fresh air. When they finally go below everyone has sweat soaked shirts except the psych doc who is perfectly dry.
Continuity mistake: About 30 minutes in, the sub surfaces to check why the ice has been hitting them. After they get outside the admiral starts to remove his parka. He pulls it off his arms and in a later shot he's pulling it off his arms again.
Continuity mistake: After the officers check out the burning sky, they start to below. Their shirts are perfectly dry but when they reach the bottom of the ladder inside they are all soaked.
Continuity mistake: While Captain Crane is at the map station, they show him drawing on the map, but his hands are Barbara Eden's hands as they are female, and wearing a bracelet belonging to her in the movie.
Continuity mistake: A saboteur sets Admiral Nelson's quarters on fire. In the first shot from the corridor, looking through the doorway, we see his cabin is filled with heavy smoke. As crewmen arrive with fire extinguishers, the camera cuts to the interior of Nelson's cabin, where there is virtually no smoke, even though there are added flame effects in the foreground. Camera cuts back to the corridor, and heavy smoke is again pouring out of Nelson's cabin.
Continuity mistake: As Nelson begins to agree with Alvarez, his arms are crossed holding the Hawaiian newspaper. A second later, they're by his sides with the paper in his right hand.
Continuity mistake: When Nelson comes into the control center, the report is that the sub was just breaking the surface. However, the prior shot of the sub travelling along showed that it was already at the surface, with the conning tower above the waterline.
Continuity mistake: In the opening, the TV newsman has holds the pencil eraser end down next to the paper he's reading from. When the angle changes the pencil is now eraser end up.
Answer: Admiral Nelson is puffing on cigars in a few scenes, and his cigars are even a source of dialogue in the film. Specifically, when his quarters catch on fire, the blaze is initially blamed on a lit cigar, to which Nelson angrily replies that he ran out of cigars before the fire ever occurred. So it's a pretty good bet that Nelson was carrying a cigar (or cigars) in his shirt pocket.
Charles Austin Miller