Factual error: When Jasmine is running in the tunnel, she kicks open the door just in time to save herself, her son, and the dog. The terrible fireball then goes right by them. They are just inside the open door, with fire and debris flying right past it. While the fire and debris might not spill in, the heatwave would still fry them. It is also likely that the fire would deplete the limited oxygen of the enclosed space.
Visible crew/equipment: At the White House, when they all watch the Soviet Special News, in the close-up of the TV's staticky reception of the news feed the reflection of White House staffers is visible. Right between the woman in a white blouse and the man in suit and tie, is the camera and crewmember, wearing a light-colored short sleeve shirt and baseball cap, moving about.
Continuity mistake: When David is looking for ice, the fridge door shelves are full of food. When Connie puts the bottle into the fridge, the door shelves are virtually empty.
Continuity mistake: When the President holds his frightened daughter, in the shot after the alien craft creates a shadow over the White House, there are photographs and a bust of Lincoln on the table beside the President - the view of the photos is not blocked by anything. In the very next close-up of the photos, things differ, such as a large framed photo of the President with the Dalai Lama that appears out of nowhere, between the photo of the First Lady and the photo of the Pope.
Visible crew/equipment: When David reaches Connie on her cell phone in the White House, as she walks away away from the wall to head towards the window, a crew member (complete with water bottle and utility belt) can be seen on the lower left portion of the screen, before he quickly scrambles away. (Only visible on VHS and fullscreen DVD.)
Visible crew/equipment: In the containment lab, when the alien awakens and begins its attack, the alien moves from right to left towards a doctor, who is backed up against a door. The crewmember who is wearing the alien costume has on a white shirt and black trousers, and the costume's straps attached to the pants are visible, as well as some wiring at the back. (Only visible on fullscreen DVD.)
Factual error: When Steven Hiller is flying through the canyon he says "Hope you got air bag" and pulls a lever to deploy the braking chute on his FA-18. The chute is then detached and lands onto the attacking alien craft. FA-18's DO NOT have a braking chute, they rely on using an arrestor hook for carrier landings and a dorsal airbrake when landing on a runway.
Continuity mistake: Several times during the last air battle, the President shoots his missiles, but a view of his plane shows that it still has all four missiles.
Other mistake: When the huge alien ship settles over the White House there is an exterior wideshot of the grounds. At the bottom of this shot it's funny how there are many tourists - adults and children, just milling around in front of the gate and across the street with a van driving along between the two sides, and not one has any sort of reaction to the alien ship. This real shot of the White House (some shots had smaller-scale models) had the CG ship edited in during post production. (Visible on fullscreen DVD.)
Other mistake: When Connie is waiting for the President the first morning she is reading USA Today. On the back there is a weather map and it is blue and green, the colours for cold in USA Today. It was a hot July day!
Continuity mistake: In the Area 51 hangar, when Steven and David are trying to take off in the alien attacker, we are clearly shown how the ship flies: Pull back on the controls, you go forward, push forward on the controls, you go in reverse. Later, in the mothership, after they have launched the nuke and are released, Steven pulls back on the controls, which should send them flying forward, but the external shot shows them flying backwards.
Audio problem: When the Knights deploy their missiles with no results, we see in close-ups as they respond that Steven is Knight 1, Jimmy is Knight 7, and another Marine is Knight 3. After Steven says, "Knight 1. Sweet Luck. Echo, Fox 2," we see a close-up of Knight 3 and hear his voice (not Jimmy's) say, "Knight 7, Fox 2", though he is in fact Knight 3, and Jimmy is Knight 7."
Revealing mistake: When Jeff Goldblum is throwing a tantrum in the hangar housing the captured alien craft, he knocks over several plastic garbage cans, one of which is clearly labelled "Art Dept" - kind of odd for a top secret underground government military research facility...(unless the can is from the Aircraft Recovery and Transport department that brought the alien ship into the hangar, in which case, it's just fine ).
Continuity mistake: When General Grey tells the President not to engage until they have visual, in the President's close-up the exterior of this F/A-18 Hornet is quite different than what was shown in the earlier shot, as the canopy closed over him. All the rivets around the canopy have disappeared and the 'danger' triangle is much closer to the name Patrick, the seat differs, etc. Plus the fact that the canopy and hull are actually one unit in the second shot.
Visible crew/equipment: At the Area 51 lab, when President Whitmore is down on the ground in pain, in the shot from inside the lab facing the lab's outer hall, the alien costume only reaches just above the crewmember's waist - the costume straps attached to his pants are visible, as well as his arm. (Only visible on fullscreen DVD.)