The clock in the wheelhouse reads 11:50 and the crewman strikes four bells. The correct strike would be eight bells and, in any case, would never be sounded ten minutes before the actual hour - 12:00 in this case.
One shot of the boat traveling toward camera shows the name of the boat on the bow is backwards. The backwards name reads Venture, indicating it's a shot reused from King Kong (1933) that has been horizontally flipped.
In a close-up of the porthole in Tertius' cabin, wires to move the detached lid are visible.
When the Captain catches Tom at the gun locker, Tom's shadow profile is cast on the wall directly beside the Captain as though the lighting is on Tom's left side, yet Tom is directly facing the Captain and the lighting is on his right side.
DVD subtitles mistake: Tertius meets the Captain's fiancée, Miss Roberts, transcribed as "Ms. Roberts." The title "Ms." has been around since the 17th century, but wasn't popular with the general public until 1971. Hitherto it was used only in exclusive writing societies which the barely literate Tertius could not have been part of.