Continuity mistake: When Jack is briefing the President, he draws a line on a map of the U.S. and tells the President to have everybody south of that line evacuated. The shape of the line changes between shots.
Factual error: The football (soccer in the U.S.) match we see relatively early on in the film is said to be between Manchester United and Celtic, in Glasgow. However, the non-MU team isn't wearing Celtic's home strip as they should be if playing in Glasgow (it's actually Boca Juniors from Argentina, in a match played in 2002) and the stadium shown is actually Old Trafford, Man. U's home ground, as shown by the advertising billboards in the background.
Factual error: The International Space Station is shown taking meteorological measurements and transmitting them to earth. First of all, there are HUNDREDS of weather satellites already in orbit for that purpose, the use of which does not require distracting astronauts from other duties. Second, the ISS does not have sophisticated earth-sensing equipment.
Visible crew/equipment: When Jack is in the library towards the end of the movie, he looks in a room and then the shot goes back to facing him. If you look very carefully, in the back of the hall you can see a person walk by. He is very hard to see.
Continuity mistake: When the tidal wave is hitting Manhattan, and the camera cuts to Laura walking behind the black woman and the cop, the woman panics and turns to her left to look at Laura, but in the following closeup she turned to her right to look and talk to Laura. (Slow-mo may be required.)
Revealing mistake: Very near the end of the movie, when the NOAA director is viewed in the helicopter as it approaches NYC, the image is reversed, verified by the David Clark logo on his headset being reversed. There are two different shots of this just a few seconds apart, and they are both reversed.
Factual error: When Sam climbs outside the ship he grabs the frozen metallic pipes and rails with both hands - one half covered with a glove, one is bare. He has no problem gripping the cold metal and he can get his hands free every time. If the moisture froze before contact, his hands would be frozen too, so that can't be the reason.
Revealing mistake: When a newscaster is mentioning that two airplanes were caught up in the storm and crashed, they show footage of the AVIANCA (Colombian airline) Flight number 52, which crashed in New York on January 25th, 1990.
Continuity mistake: The first time we see the black bear cage, the sign (and the entire shot) is a reversed image. Twenty five minutes later, we see the black bear cage again and the sign is correct.
Factual error: The aircraft flying to rescue the British Royal Family are described as belonging to "an RAF search and rescue squadron." However the middle aircraft has white and green striped camouflage painted on it, which is a pattern only used by aircraft in 845 Naval Air Squadron (a Royal Navy unit).
Continuity mistake: When Sam and his two teammates are on their way to NYC for the competition, the airplane gets hit by turbulence. Two attendants go to the back of the aisle with the drink cart, when the plane starts to shake, and in the long shot of the aisle (from the head to the back) one of them is in front of the cart and the other one is behind. However, both are behind the cart in the close up, when they try to prevent the cart from hitting anybody.
Factual error: NOAA headquarters is shown to be in downtown D.C, when in fact it is just outside of the District in Silver Spring, Maryland.
Plot hole: When you see the shot of New York, just before the scene where the apartment lights go out, there are no lights on in the buildings, or car lights in the street, although it is dark. The lights should still be on as there has not been a power outage.
Continuity mistake: Just after Jack comes out of the New Delhi conference, he is talking with Terry Rapson. At the right of the screen at the stand, there is a guy with a red hat/turban and scarf and no other people behind him with turbans. However, in Terry's close-up the man wearing the red turban has vanished and there are a lot more people in the background wearing turbans.
Revealing mistake: In the scene where Dennis Quaid jumps over the ice crevasse to the other side, note the position of his ice axe, which is strapped to the right side of his hip. When he jumps back over with the metal tubes in his hands, he balances a little, then falls. We see his gloved hands disappear as he falls into the crevasse. The next shot shows he is holding onto the ice axe, which is embedded into the ice with his left hand. In reality he would not be able to unhook the ice axe so quickly and then put it in his left hand and thrust it into the ice. Remember what gravity does.
Continuity mistake: When we see the news report on the TV, you can see that people are taking bottles of water from the shelves. Beside the TV you see a person's hand on the right side of the TV and a black tea flask as well. In the next shot the person's hand is much further away from the screen and the tea flask has also been moved to the opposite side of the TV.
Continuity mistake: When Jack is trekking north to Manhattan with two of his colleagues, one falls through a glass ceiling and the other cuts his right hand trying to save him. Despite the fact that we see his hand bleeding profusely, you can see in the subsequent scene that his right hand is just fine.
Continuity mistake: When T.J. is talking with the homeless black guy who is sitting on the floor telling the student how to keep warm, the guy throws the student a book to rip up and make himself warm. When he throws the book, the student is grasping the book at the bottom with his left hand, but in the following shot his left hand is at the top of the book.