Character mistake: In the Iraqi Desert, when the British soldiers speak of the casualties and losses, one of the British soldiers mentions the loss of the Belgian contingent and possible reinforcements, then makes a reference to the "Golan Straits"; there is no such place.
Factual error: The missile launched by the B-2 is made-up. The nuclear missiles carried by the B-2 are powered by a small jet engine, not a rocket motor. The last air-launched, rocket-powered, nuclear missile was withdrawn from USAF service in 1990, before B-2s had even been delivered to the Air Force. Plus, these missiles are very accurate and have a range of hundreds of miles. Why get so close? Finally, the B-2 pilots have no flash blindness protection. No blackout panels on the windows, or special goggles that darken when exposed to bright light. The tinted visors on their helmets isn't good enough to block out the flash from a nuclear detonation. (01:36:20)
Factual error: The firewall that destroys Washington DC is all wrong. When the destroyer blows up the White House, as in NYC and LA, it would have created a ring of fire that would have spread outwards. The White House is in a North Westerly position from the Capital Building, so when the fire wall hit the Capital Building, it would have hit from the side - but, instead, it hits from the back/front. (00:47:30)
Other mistake: When the President and the others arrive at Area 51, the sliding glass door to the laboratory that the staff member opens with his key and numerical key code opens before he finishes entering the code.
Visible crew/equipment: When President Whitmore is on the phone with his wife (their daughter Patricia lies on the bed), telling her he wants her to leave LA and a chopper will take her to Nellis Air Force Base, a Secret Service Agent appears at the doorway and the actor's mark is visible on the floor. (Only visible on fullscreen DVD.)
Factual error: When Air Force One is taking off, the fireball should not be that close. The heat from the fireball would keep the wings from getting any lift as hotter air is thinner. Since the fireball is hot enough to explode steel and concrete it would surely have ignited the 45,000 gallons of fuel in the wings and melted the rubber tires. Had the plane actually been able to get its tires off the ground, the 'rolling' effect of the fireball and the rapidly rising heat being below and behind the plane would have caused it to do a 'negative angle pitch-over' or forward somersault right into the runway.
Other mistake: In the scene immediately after Jasmine, her son, and their dog escape the fireball in the utility closet, they emerge from the wreckage to find everything destroyed. But in the background there are two palm trees still standing, with leaves and branches still intact. Isn't it logical that a huge fireball such as that would at the very least burn the leaves off the tree?
Factual error: The opening scene shows the Apollo 11 landing site. Aside from the previously mentioned plaque incorrectly shown being on the ground, the scene shows a pristine American flag standing upright. The Apollo 11 flag was actually knocked over when the Lunar Module ascent stage launched. Plus the American flags left on the moon are bleached white with no color, due to UV rays and massively direct sunlight - and they are probably disintegrated, due to micro meteors and solar destruction. (00:00:45)
Visible crew/equipment: When David introduces the idea of a virus, the first time Major Mitchell shoots at the Coke can the two actors' marks are visible on the floor in front of Julius and Connie, as well as a brown rug at their feet, that are not in other shots. (Only visible on fullscreen DVD.)
Factual error: When the alien ship arrives in Washington DC, its shadow goes over the Lincoln Memorial from the bottom of the Lincoln statue to the top. Since the saucer is heading over the National Mall and the Lincoln Memorial faces the Mall, the shadow should have gone from the top to the bottom. (00:21:40)
Continuity mistake: When David squeezes his dad's shoulder, after he just won chess, David has a severe bruise on the middle fingernail of his left hand, which disappears as soon as he gets back to work.
Factual error: David is in New York playing chess and then goes to the station riding his bike through the office. When he goes past the vending machines, the water machine is Arrowhead branded, which is a California / west coast water brand - not on the east coast. (00:07:00)
Continuity mistake: In the Oval Office, when David says, "They're using our own satellites against us," the grandfather clock is about a foot away from the doorway behind him. In the previous wideshot, when Alex appears at the doorway, the grandfather clock is farther to the right, nearer to the other curtained doorway.