Continuity mistake: Just before Captain Ashland renders Captain Marshall unconscious, Ashland hits Marshall's left hand with the butt of his rifle, bloodying it in the process. When Marshall first comes to, continuity is in place. When they cut back to him, and he rises, it's his right hand that's now bloodied. Shortly thereafter, Marshall is shown running on deck, holding his left arm. When he descends some stairs, the blood is back on his left hand and his right is clean.
Continuity mistake: When the Death Ship rids itself of its two lifeboats, Captain Marshall and Nick watch as the first hits the water. It's full of debris. Captain Marshall and Nick then move to the other side of the Death Ship in an effort to prevent the second lifeboat from being dumped, a distinctly different boat sans debris. When it hits the water, the editors cut to an image of the first boat.
Continuity mistake: In an early shot of the survivors on their raft, Captain Ashland (Kennedy) can be seen lying on the deck prior to the scene where he is pulled from the sea and brought aboard the raft.
Visible crew/equipment: As George Kennedy appears on the bridge in full German uniform and calls Marshall up, two camera crew can be seen to the left of the bridge. One on the ladder pointing a large camera at Kennedy. (00:51:55)
Continuity mistake: When Mrs. Morgan notices the peppermints, they're individually wrapped. When she picks one out, they're unwrapped.
Continuity mistake: As the survivors are first seen from the deck of the Death Ship, they are up and paddling. As the scene shifts to their view looking up at the ship, they were apparently asleep, except for the captain.
Continuity mistake: The amount of blood in the shower varies from shot to shot. One moment, it's ankle deep, then the drain is visible, then ankle deep again.
Visible crew/equipment: When the survivors of the cruise liner sinking approach the ominous ship, it's supposed to be deserted, but as a window opens, a person's arm holding a stick to open the window is visible.