Continuity mistake: When Steven Hiller goes out to get the paper, the paper has a string around it to keep it closed, yet he opens it up as if it was only folded. (00:25:15)
Other mistake: At the end, when Steven and David's ship is released from the clamp in the mothership and are leaving, Steven never puts on his seat belt. Surely from all the twists and turns, not to mention the little nuclear explosion, he would have been tossed around just a little. (02:10:30)
Continuity mistake: When Dr. Okun and David are inside of the alien ship, and Dr. Okun shows him the scrolling green lines on the console he says that they don't know what they are. David says it's the same thing as their countdown signal and they always move together. Yet when Steven is flying their ship through the mothership, the lines go horizontal, spread apart, and even turn blue in some parts. (01:21:00)
Continuity mistake: When David and Dr. Okun are inside the alien aircraft having a look around, it cuts to a front view of them, and if you look to the right two other scientists walk in. The scientist with the mustache and beard stops and looks, and the other walks a bit further and peaks over, then in the following shot you can see this action again. (Special Edition.) (01:18:20)
Continuity mistake: When Captain Hiller begins his attack with the rest of his crew from El Toro, when we see the room where the General and the President are, a man says "Missiles have been fired", it shows on their screen a countdown of "metres to target". It does a countdown of 5000 to 4000 twice, and 4000 to 3000 twice. Also, when we next see the countdown before the missiles hit the shield, the last number is 49m, then the following shot of this number it says 107m. (00:57:50)
Continuity mistake: In the middle of the film when the President is in Area 51 looking at the alien aircraft, there is a shot from the back and you can see that the General is not standing really close to the doctor, in the following shot from the front he is standing side by side with the doctor. (01:14:10)
Other mistake: When we see the Russian picture of the map where the UFOs are going in their country, the Cyrillic for Petrograd is incorrect as there is a Western lower case "r" in the city's name. The small "r" is close in appearance to the Cyrillic "g" which has a straight line (east to west)at the top of the letter instead of the curved line that we associate with our lower case "r".
Continuity mistake: The alien saucer that arrives over Los Angeles is said to be approaching off the California coastline, yet it is specifically shown approaching from Imperial Valley, which is to the east/southeast of Los Angeles.
Continuity mistake: At the MCAS El Toro ruins, when Steven's chopper is heard overhead, the First Lady sits up and leans on her right arm with her left arm over the blanket. In Jasmine's close-up, the First Lady is lying down fully covered by the blanket, but when it cuts back to the First Lady her position is back as the first shot.
Audio problem: After David's rant about burning the rainforests, etc, when he's on the ground Julius takes the bottle out of David's hand and we hear the sound of the bottle hitting the floor. But Julius still has the bottle in his hand, then puts it down two shots later - with no sound obviously. (01:35:30)
Visible crew/equipment: When Russell lands his crop-dusting plane and Miguel rides up alongside on his motorbike. The equipment used to help stop the motorbike, at the right position for the close-up, is visible on the ground - but it's gone in the wideshot. (Only visible on fullscreen DVD.)