
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. (00:31:40)
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.
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. (02:29:15)
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. (01:33:35)
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. (00:35:55)
Other mistake: When Jack draws Rose the hand that is shown in close-up is much too old to be his. [It's James Cameron's hand - still a mistake, but there's why.] (01:23:40)

Revealing mistake: When Jack spreads the handcuffs over the pipe, we have a very clear close up shot of the links connecting the cuffs. In this shot you can see that the link nearest Jack's right hand is broken and not a complete link, therefore he should be able to separate the cuffs without going through the axe sequence. (02:00:05)
Continuity mistake: When Jack is teaching Rose how to spit, then gets caught by some ladies, he has a glob of spit on the far upper right side of his chin, then the shot switches and it is now on bottom middle and a little to the left of his chin. (00:52:25)
Suggested correction: The glob doesn't move from the right side to the left side.
Factual error: When Jack and Fabrizio are searching for their cabin, Jack can be heard muttering the cabin number - G60. Not only did G60 not exist, it would have been in Second Class, as third class cabins weren't prefixed with their deck letter. Cabin 60 itself was on F deck and bunked 8 people rather than the small cabin in the movie. (00:27:10)

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. (00:27:45)
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. (02:40:40)
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. (02:12:50)
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. (00:32:30)
Continuity mistake: Right after the 1st smokestack has fallen and crushed Fabrizio, it is seen from above creating huge sprays of water. The problem is that the smokestack looks nothing like the Titanic's. You can see the top and there is no black whatsoever. And to make it stranger, there is a cable attached to it and then one below it, both on the peach/orange color, and not the black. (02:36:10)

Continuity mistake: When Rose attempts suicide she is holding onto the railing while standing on the outside. In some shots the black lace from her dress is held under her left hand, in some it isn't. (00:37:40)
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. (01:36:40)
Suggested correction: Wrong. I saw this scene many times and I never noticed anything like this. Everything looks perfectly normal to me. I would need to see a picture to see the evidence.
Revealing mistake: In the suicide attempt scene, after Rose climbs over the railing, you can notice banding of the night sky a couple of times - that appears on both VCR and DVD. (00:37:15)

Continuity mistake: The length of Rose's fingernails changes noticeably throughout the film. In some scenes, her nails are very short (during the "flying" scene), and in other scenes her nails are a lot longer (when she takes the comb out of her hair right before Jack sketches her). (01:18:40 - 01:21:20)

Continuity mistake: At the beginning when Jack and Fabrizio go to the front of the ship, you can see the anchor section at the front, yet when Jack is waiting for Rose, the camera pans up, and its a completely different design, than from the first look at the beginning. (00:30:10 - 01:17:10)
Continuity mistake: When the funnel tips over it breaks at the bottom. The camera cuts to Cal, then back to the funnel, and it breaks again. (02:30:00)