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. (02:02:15 - 02:03:15)
Continuity mistake: David calls Connie at the White House and she walks toward the divided pane windows, then pulls the curtain to the side. In the exterior shots facing her the pane's white grille is between her hand and face, but in the next interior shot looking out, there is only clear glass, though we should see the grille just as we see both sides of the curtain with her hand holding the right side. (00:38:25)
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. (02:03:25)
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. (01:24:55)
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. (02:00:25)
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.
Continuity mistake: When David is getting drunk and he's talking to Connie, at one point he slams the bottle down on the counter and a little liquor sprays up out the opening. Then they talk for a second, and he picks the bottle back up to pour himself more, but he now needs to unscrew the cap which was just lying next to the bottle. (01:25:45)
Continuity mistake: When Captain Hiller is dragging the unconscious alien across the desert, the sky alternates between overcast and perfectly sunny depending on if it's a close up or far off view of Hiller. (01:07:30)
Continuity mistake: The scene after Jasmine's club pole dance, she is with her girlfriend in the dressing room. She is warning her girlfriend not to go to the alien rooftop site. Jasmine walks away undressed, but comes out a moment later with her shirt and pants on, and though she put her clothes on over her dance outfit it is still too quick to accomplish in that brief moment. (00:36:25)
Continuity mistake: When Captain Hiller is in his dress uniform in the house and then outside beside the car, before he heads back to El Toro, the epaulette on his shoulder is out above the collar, in the next shot it is under the collar (where it belongs), but in the very next shot, it is out again. (00:29:35)
Continuity mistake: Just before President Whitmore gives his rousing speech, when Major Mitchell is talking into the mic, asking for all flight crews to report to their designated areas, the camouflage pattern on his uniform is entirely different from the uniform he wears in the previous and following scenes that he appears in. (01:51:20 - 01:55:10)
Continuity mistake: When Steven walks across the lawn to get the newspaper, a few feet away from the window there is a tall rosebush behind a white bench seat with a high back. Later, when Steven packs up to head back to the base, Jasmine pulls open the curtains and right outside the window is a tall flowerless bush. (00:25:20 - 00:29:10)
Continuity mistake: When Jasmine sees the approaching fireball she grabs Dylan from the car and begins to run. In the shot from behind, there are double-yellow lines on the road at her feet reaching into the distance, but in the shot facing her the lines have vanished, though she did not change lanes.
Continuity mistake: At the White House, after the President says good morning to Connie and walks past her, she stands up then places the two folded sections of USA Today in her left hand - with the headline section covered, as she holds her briefcase in her right hand. Next shot from behind, she is now holding a section in her right hand with the briefcase, as she reads from the headline section held in her left hand.
Continuity mistake: In the briefing scene at El Toro prior to the first counter-offensive, Lt. Colonel Watson, the briefing officer, has silver oak leaves on his collar (Marine Lieutenant Colonel). A few scenes later, when El Toro is under attack, Lt. Colonel Watson is shown again, but has been demoted two grades and has two silver bars on his collars (Marine Captain).
Continuity mistake: When President Whitmore boards the chopper and then Air Force One, he wears a white shirt with both thin and thick stripes. The stripes on his shirt collar constantly change, and nowhere is it more noticeable than when they arrive at Area 51. It varies between only one thick stripe, which changes from the top of the collar to the bottom, or two or more thick stripes, all surrounded by thin stripes. Wardrobe Dept bought identical shirts for the actor to wear, but the collar stripes just don't match up between scenes.