Continuity mistake: At the part when Jack or Rose (I can't tell which) wipes their hand on the fogged up window, they show it again in the next shot and you can definitely tell it's a completely different handprint. (01:32:00)
Continuity mistake: When Hockley and Lovejoy find the drawing of Rose in the safe, Hockley is holding the drawing which has been secured in some kind of brown manila folder. A split second later, Hockley reads the note Rose left while still holding the drawing (and even angrily squishing it slightly with his hand), and it is not in a manila folder. (01:32:40)
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 the two guys in the watchtower on the front of Titanic spot the iceberg, the shot cuts to the helmsman. Behind him the clock says 11:40pm, but when we next see the clock 5 to 10 minutes later its still on 11:40pm even though almost 10 minutes has passed. (01:34:35 - 01:38:50)
Continuity mistake: When the engine room gets the order to cut power to the engines, the wheel that one of the engineers is turning is black, however a few minutes later the wheel is gold. (01:35:00)
Continuity mistake: When the alarm sounds in the boiler rooms, the officer shouts "Shut all the dampers." We see all of the firemen shut all the loading doors to the furnaces. But a few clips later, when water pours in, the water flows past open furnace doors. (01:35:00 - 01:37:20)
Continuity mistake: We see Mr Andrew walking through the 1st class cabins just after hitting the iceberg. He has 4 blueprint rolls under his arms. We then see him out on deck while discussing the situation with a few other men and the rolls have gone. As he gets to the office with Captain Smith he has the rolls again. (01:39:20)
Continuity mistake: The way the necklace is held after it is found in Jack's pocket changes instantly. In one shot the steward is gripping the chain. In the next, the chain is draped over his fingers. (01:41:10)
Continuity mistake: After handcuffing Jack, Lovejoy says the initials on his coat and Jack turns to Rose. A frame later, from a different angle, he is looking away. (01:41:35)
Continuity mistake: When the diamond is found in Jack's pocket the way Rose's hair is messed up is different in every single shot. (01:41:45)
Continuity mistake: When the Captain tells the morse operator to make an emergency call, the position of the papers and pencils in front of him move around between shots. (01:44:50)
Continuity mistake: When Rose Cal and Rose's mother are standing on deck, Rose says "oh mother, shut up ", before the face shot of her mother you can see she is already looking at Rose in the previous shot, then she whips her head around again to look at Rose. (01:52:10)
Continuity mistake: When Jack is cuffed and has just looked out of the window, we have just seen his window is about 10 feet underwater, but when we see him banging his handcuffs, we can see the top of the waterline in the window. (01:52:40)
Continuity mistake: After Rose refuses to get in the lifeboats there's a shot of handcuffed Jack crying for help. A frame later his fringe has swapped from combed to parted. (01:52:40)
Continuity mistake: Just after Rose leaves Cal, we get an underwater shot panning down on Jack, showing that the window he's standing next to is fully submerged. However, interior shots after that show air around the upper edge of it. It's not trapped air: it's constantly bouncing around, in a wave-like pattern. (01:53:10)
Continuity mistake: When cuffed Jack is screaming for help, you can see the water level in the porthole in the background although the room in which he is cuffed, has already been shown to be completely under water. (01:53:40)
Continuity mistake: In the scene where Jack is handcuffed water starts running into the room the desk. At that moment the desk, which had been out of reach before, is moved closer to Jack and standing diagonally, so that Jack can climb on it. This happens before things get moved around by water or gravity. (01:54:45)
Continuity mistake: When Rose enters the cabin where Jack is handcuffed, the pillow on the berth behind appears/disappears between shots. The black jacket on the desk and items on the shelf also disappear. (01:55:40)
Continuity mistake: When Rose finds Jack handcuffed, the papers by the corner of the table next to him swap from being white coloured to yellow, plus being on the very edge or not, depending on which angle is shown. (01:55:40)
Continuity mistake: When Rose leaves Jack to find help, she runs and wades through water that, at times, is above her waist. However, when she is seen from the back after going up a staircase, the water level on her coat changes a few times and in one shot the coat shows no water line at all but is completely dry. (01:56:20)
Chosen answer: During the several years it took to construct the ship probably, or in any of the supplies/food brought on board, or in the furniture brought on board. A single pregnant female rat can be responsible for thousands of rats in a very short space of time (the offspring are not too choosy about who they breed with).
Soylent Purple
A pregnant female rat could have made a home in a underneath a third class couch and had the other rats then all the females would have baby rats quickly.