Continuity mistake: When the Red Dust is spread, there is a brief shot of some California citizens watching, and we see the Bernsteins among them. But the actress at George Mofogen/Mr. Bernstein's side is not Bonnie Bartlett, who played Mrs. Bernstein in the first two episodes.
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.