Deliberate mistake: As the sub rises backwards to the surface, the stern emerges from the water at a steep angle, then rises near-vertically so that the boat is virtually standing on the tip of its bow. Anything left loose on a countertop would surely fall off. But when the boat falls onto its belly, a close-up shows a pistol sliding off a sink counter into the hand of the Captain- because it's dramatic and cool looking, yet extremely improbable- especially considering that an open tin of shaving foam, its lid and a foam brush all lay on the same counter, undisturbed.
Factual error: In the close up shot showing the record on the record player, the label correctly identifies the song that played as Benny Goodman's "Sing Sing Sing (With a Swing)" but the label also states it is a "Swing Classic," a classification only used when the record was later reissued. The label is inappropriate for a World War II time frame.
Trivia: When Claire is in the Captain's quarters and turns to see the dead Winters' lying in his bunk, two shots that follow show Olivia first turning away from Winters, then emerging from his room into the passageway. Both of these shots were filmed in reverse, then played backwards to make them look more eerie - note the odd movement of her hair, especially in the latter shot.