Revealing mistake: When Rose and Jack first enter the boiler room, they run towards the right. If you look closely you can see the reflection of the worker in the back to the left in the mirror they use to make the bolier room look longer. In the next scene they are running in the opposite direction, because the set is so small due to the mirror, and once again you can see the same reflections caused by the mirror.
Continuity mistake: When Rose has just boarded titanic and is looking through her "finger" paintings, she is holding a painting, then slides it down her fingers. When she slides it down, she slides it almost to the end of the painting's frame, but in the following shot she isn't even close to the edge/end of the painting.
Audio problem: When the Captain is watching the overturned boat trying to be launched, there is a crew member working on the davit, causing it to make a rapid clicking noise. But soon after the noise stops, the crewmember is still turning.
Continuity mistake: When Rose is running to get to the stern to throw herself off she starts by running on the first class A-Deck promenade. Then when the whole stern of the Titanic is shown sailing, Rose runs out from the 2nd class B-Deck promenade, a deck down. The only way that these two promenades were connected was by two ladders, which Rose passes when she keeps running. It makes no sense to go down the ladders, go forward, turn around and head back to the aft part of the ship.
Continuity mistake: When Rose and Jack run outside after making love in the car, you will notice a shot of the men in the lookout tower where you can see their breath due to the extremely cold night. But when the shot goes to Jack and Rose, you will notice that you cannot see their breath but also Rose does not seem to be affected by the cold even though she is wearing a thin dress with no sleeves.
Continuity mistake: When Jack is howling at the front of the ship, he puts his arms up. His left arm is behind the rope, but in the next shot of him, his arm is in front of it. In the next shot, it is behind again.
Revealing mistake: In the engine room as the ship is sinking, the smoke and steam coming from the machinery rises at the same angle as the ship, about 45 degrees. So, the shot was filmed level, then tilted afterwards.
Continuity mistake: After Rose has been persuaded to step into the lifeboat the camera is on Cal and Jack for quite some time when Cal reveals to Jack that there is no arrangement in his benefit. During all this time the lifeboat is being lowered, but when the camera cuts back to Rose she can still make eye contact with Jack almost at level.
Revealing mistake: Right as the Titanic hits the iceberg it does an underwater shot of half the ship. If you look closely, it really is only that half of the ship. The 3/4 size model they built was only half a ship, and they clearly didn't frame the shot right.
Factual error: In the shots taken in the grand staircase, the lights on the ceiling are flush with the ceiling itself. The lights in the actual Titanic's grand staircase were mounted via a small pedestal. Earlier in the film when the submarine is exploring the grand staircase, there is a shot of one of these same lights except this light actually has the original pedestal.
Continuity mistake: When Rose, Cal and the others sit around a table talking and drinking, and Mr Ismay says something. His hands are locked together by his fingers, but in the following wide shot his left hand is down by his knee and his right is holding a fork with food on it. Also, Rose puts the cigarette holder to her mouth and takes her left hand away from it but in the following shot her left hand is still on it.
Factual error: The lifejackets in the movie have the wrong number of cork pieces. In real life each side had six pieces but in the movie there are twelve.
Factual error: Margaret Brown never went by the name of "Molly" Brown during her lifetime. It was not until after her death that she was referred to as "The unsinkable MOLLY Brown".