Revealing mistake: Near the end of the film when Jamie is 'talking on her phone' in the bathroom you can see in the mirror that she hasn't actually answered it.
Revealing mistake: Despite her claiming to be topless you can see what looks like a tube top on Kristen Wiig during her attempts to get the state cop to notice her.
Suggested correction: No, she's not wearing a tube-top. Looked up the scene on online. She has her hands covering her nipples, and her passenger Helen has her arm up in a gesturing manner partially covering her breasts, but there's absolutely no tube-top in sight. (I think you may be seeing part of Helen or Wiig's arm and think it's part of a tube-top).
Revealing mistake: When the LG billboard changes to the blue moon ad, the LG billboard is still visible on a reflection on the glass on the front of the MTV studios building.
Revealing mistake: As the guy is being pinned down by the giant hooks you can see for over a minute he can simply escape and slip his hands out. (00:52:30 - 00:53:30)
Revealing mistake: The gang is starting to argue as they are running behind schedule. The big guy is holding Nicole Kidman at knife-point. The camera zooms in on her breathing heavily...so heavily that the 'metal' blade of the knife bends up and down. (00:29:00)
Revealing mistake: When Donovan witnesses a fatal traffic accident on a rainy night, he suffers a mild heart attack and collapses in the street. Although he's lying on his back, unprotected from the downpour, surrounded by rain striking the pavement in both foreground and background, closeups show that no rain strikes his face, his felt hat, or his clothing. (00:12:20 - 00:12:50)
Revealing mistake: Locked out of the house, Katie has to wander around naked. Or rather, in her skin-colored tight fitting underwear. (00:16:22)
Revealing mistake: In the scene of the 20th game (the following shot after Brad Pitt leaves the field) we see Jonah Hill looking at him. An extra to the left pulls out his smartphone (which in 2002 was years away from release) and proceeds to take a picture of Jonah Hill.
Revealing mistake: In the scene when they are travelling in the RV, the tea in the glass is perfectly still, even when the RV is obviously in motion. The tea should be jiggling in the glass.