Other mistake: After Jack and Rose are "done" in the cargo hold, they come out onto the bow of the ship laughing. Whilst the door they used to get onto the bow does lead to the cargo hold, inside you have to go down a flight of stairs and are greeted by a cast iron hydraulic door which can't be opened from inside the cargo hold, and would close automatically if the control wheel wasn't being held. The only way they would have been able to get out is by running back through the boiler rooms.
William Glen
25th Feb 2019