You can see scaffholding behind Cal when he gets out of the car in the boarding scene.

Rose's paintings were actually on the Titanic.

The 'Lake Wissota' Jack mentions wasn't even built in 1912.

The suite occupied by Rose and her entarage didn't even exist on the real ship.

"Cal's Crying Girl" was played by twins.

If you followed Thomas Andrew's directions to Rose, you would find the office of the Master at Arms.