Deliberate mistake: In the scene at the start of the movie with the "authentic" piece of film, you can see a girl with a hat waving to the people at the ground. When the ship is leaving port in the film, she and others are in the same positions, only in reverse, because the first "authentic" shot is the same shot, only mirrored. (00:00:40 - 00:25:30)
Factual error: All deep sea submersibles that travel to depths of two or three miles fall to the ocean floor with no power on. At the start of the film, you see MIR1 and MIR2 pan past the camera with all their lights on. The lights should be off to conserve electrical power. The journey to the sea bed takes two and a half hours. (00:02:00)
Continuity mistake: When the submarines are down at the wreck they are shown looking at the enclosed promenades at the bow of the ship. When the camera backs up in one scene to reveal more of the ship there is a pole that is broken. Then in the next shot you see the same area, with the same pole intact. Apparently because both subs are seen during the broken pole, that was not the real Titanic, while the unbroken was. (00:03:00)
Continuity mistake: At the beginning of the film, when Brock is being taped in the submersible, the sub is already underwater. Only seconds later, if you look out the circular window, it's the reflective tops of the waves. Did they just rise up to the surface suddenly? (00:03:20)
Other mistake: After the "flying" scene, the story cuts back to real time. When it starts to transition back to the flashback, the camera zooms in on a television screen with the fireplace in it. This screen is 1) also used in the beginning of the movie 2) impossible, seeing how there was only one ROV in that room, and it shows the ROV in it. (00:06:15 - 01:20:10)
Revealing mistake: Notice the land in the background of the ship which is supposed to be in the middle of the North Atlantic. It is in one of the whole shots of the boat which has Brock and his team on it. (00:08:30)
Continuity mistake: In the beginning, when the safe is being opened, there's a close-up of the grinding wheel digging into the metal. In the next shot the crewman who does the job is only kneeling down, while the grinding sound is already there. (00:09:00)
Visible crew/equipment: When old Rose is traveling in the helicopter at the beginning of the movie, the skids of the filming helicopter can be seen reflected in the window of the one Rose is in. (00:13:02)
Continuity mistake: At the very beginning of the film when Brock is talking with the big guy, they walk up stairs turn to the right, and right in front of them is a large piece of the ship with a no smoking sign on it, yet in the following shot, the large piece has turned into a very small piece, not even enough room for the sticker. (00:13:35)
Continuity mistake: When the old Rose arrives on the Keldish, she is unloaded from the helicopter sitting in her wheelchair. The two pilots are helping from above, but afterwards they disappear inside the helicopter from one shot to the next, which is too fast as the rotor noise suggests continuity. (00:14:20)
Visible crew/equipment: When Rose says her line "Yes, I would like to see my drawing" when she is in her stateroom with Lizzie, the shadow of what appears to be a boom mike (behind her and to the left) can be seen dropping down prior to her line and then going back up afterward. (00:15:00)
Factual error: It is fairly well known that James Cameron built a virtual full-size replica of the ship for shooting the exterior scenes. However only the starboard side of the ship was constructed in full, facing land (port side only down to B deck); when scenes were required that need to show port side Cameron generally employed a method known as 'flipping.' For example, in the early scenes of the film we see Titanic at 'Southampton' and passengers boarding the port side. This was achieved by reversing the camera angles. All the signs on passing carriages/vans and White Star logos were printed back-to-front so that when the scene was printed it could be reversed, thus showing both sides of the ship. The problem is that in reality the starboard side of Titanic was not a mirror image of the port side. On one side of the forward boat deck there were entrances to the First Class Gymnasium and forward Grand Staircase, while on the other side there were the windows of the Officers' Quarters and the entrance to the Wireless Room. On Cameron's Titanic you get to see the gym etc. on both sides of the ship. (00:20:20)
Factual error: The car which brings Rose and Cal to the docks at Southampton has an RB registration plate. But RB wasn't introduced as a car registration index mark until 1929. (00:20:30)
Continuity mistake: Rose steps out of the car, sees the Titanic and says "It's as big as the Mauretania" while she holds her hat. A frame later, from a different angle, her arm is down. (00:21:00)
Continuity mistake: When we see Rose at the start she says she doesn't know what all the fuss is about. As she says this she has her hand on her hat, but after the angle changes it isn't. (00:21:15)
Continuity mistake: After Rose sees the Titanic, Cal replies "it's 100 feet longer than the Mauretania", with nobody behind him. Right then the angle changes and his chauffeur appears. (00:21:20)
Suggested correction: Lovejoy is seen further back. When Cal says its 100ft longer, he turns to help Ruth out of the car and Lovejoy is still further back. However due to the new angle, he appears closer.
Continuity mistake: Look closely at the location of Rose's beauty-mark the first time you see her at the dock. It is on the opposite side of her face during the rest of the movie. (00:21:30)
Continuity mistake: Cal checks his pocket watch when getting ready to board the Titanic. In one shot he has his walking stick raised. In the next shot it has vanished completely. (00:21:50)
Revealing mistake: When Cal steps out of the car just after the beginning of the movie, you can see behind him the back of the Titanic replica still incomplete, with the internal structure totally visible. (00:22:06)
Revealing mistake: When we see the dogs being led on to the ship at the very start, look behind them and there is a woman on the walkway waiting for her cue to start walking. (00:22:10)
