Other mistake: At the end of the film when they arrive in NYC looking for the library, we know that they survived because they are inside with a roaring fire burning. But where is the smoke up above, as Jack Hall approaches? There must be a chimney, or else they would have all died of asphyxiation.
Other mistake: In the scene where the first storm appears, you see little windmills spin and trees affected by this wind. However, the hair of the old man walking out of his house (in the same shot) is undisturbed. (00:23:30)
Other mistake: At the end when Jack walks into the room where everyone is and shines his flashlight around, you see the nerd and the rich kid with the librarian in the background. Then you see a girl next to Sam's girlfriend. Where did she come from?
Other mistake: During the tornadoes in LA there is a large sign that slams into the news anchor. The speed and angle of the sign would throw the anchorman at least towards the van that it goes over. Even if his body did hit the ground with the sign flat on top of him, his body would have moved towards the van if not slid far beyond it.
Other mistake: A huge majority of the crew listed in the first half of the credits are French Canadians, their name spelled properly, accents and all. As seen in the UK, all the times "è" should have been written, it was replaced by a "Ø", for example HélØne and LafreniØre. Very noticeable when you know about it, and most probably caused by a sloppy conversion between two software, and no one proofchecking the credits before putting the movie out. Maybe fixed for home release.
Other mistake: Towards the beginning of the movie, one of the characters starts the ignition on his truck. If you look carefully, he turns the key the wrong way.
Other mistake: Near the end of the movie, in New York, once the storm has cleared, ships seem to be pointing out of the ice at all angles. For a while before the water froze over, the ships would've had enough time to either level out or sink if they had been ruptured in some way. Also, there is no way they could be touching the floor of the harbour, seeing as how the water not only rose, but it was already deep enough for ships to pass without difficulty. (01:46:40)
Other mistake: At the beginning of the film, where Jack falls into the crevice, he's got nothing in his hands. In the next shot, you see he's clinging to the side of the crevice with an ice pick that has mysteriously appeared in his right hand.