Other mistake: When passengers are supposed to be panicking on the deck of the ship, there is a woman close to the camera who is obviously enjoying herself immensely.
Factual error: Considering the list of the ship (how far it's tilted in the water), its not until they make it to the upper deck that the passengers start acting as if the ship is tilting. Before they get to the top, they are walking normally, and the water is perfectly level with the floor.
Revealing mistake: In the final shots when the ship is sinking and Henderson and his wife are walking up the deck before jumping off, you can see the walls wobble as its not a real ship but a set.
Continuity mistake: When the boiler explodes, Robert Stack runs into his daughter's bedroom, looks down the big hole and the cabin below has nobody in it. He tries to save his daughter and the camera angle shows someone lying on the floor next to the hole. Looks down for the third time, and the person lying on the floor is gone again.Tom O'Donnell