Factual error: When the world celebrates the Visitors' flight, there are scenes of joyous people from all around the world. Curiously, in each of these scenes it is daytime - even in Italy, China, and India, where it would be either night or dawn, given that L.A. time of the attacks is between 11 and 12 AM.
Revealing mistake: When Julie is almost converted, a fake Donovan bursts in and starts firing a blaster rifle. Look closely at the first shot: the rifle is held way too high, so the shot should have gone into the ceiling; yet the blast goes straight forward.
Continuity mistake: When Julie and Robert infiltrate the hospital using the forged passes, the pass is shown twice as it is inserted into the reader. In the first shot, it slides in down whole, but the reader is still buzzing. In the second, the card starts sliding in again.
Plot hole: In the opening scene we see Mike and Kyle driving in the truck. Kyle remarks that Mike has been driving since midnight and it is broad daylight outside. So they have supposedly been driving for several hours. Yet they start talking about their mission as if they have only just got in to the truck. As anyone who has been in that kind of situation knows, everyone always discusses the important stuff at the start of the journey, so it is clear that the scene has been poorly scripted. (00:02:00)Daz