Character mistake: When Chessy confronts "Annie" when she's presenting her with the big breakfast, she's talking about when Annie was on the phone the night before. Then she says her father overslept, when she actually meant to say and "and you overslept," as the conversation doesn't make any sense saying that the father overslept. (00:58:00)
Character mistake: In the President's speech he says that 'The Bible calls this day Armageddon'. That is not correct. In John's Revelation 16 verse 16 it says 'And he gathered them on the place which in Hebrew is called Harmageddon'. Even aside from spelling variations, Armageddon is a place, not a point in time.
Character mistake: In the scene when Gillian and Sally are dragging the boyfriend in to put him on the table Gillian says, "Watch his balls Sal". It is in Nicole Kidman's native Australian accent and the rest of the movie she speaks with a Northeastern US accent.