Revealing mistake: During the bedroom scene with Felicity and Fat Bastard you can clearly see the air hose that fills his suit when he rolls over in the bed. (00:49:10)
Revealing mistake: When Sonny is on the payphone, you can see Julian mouthing something to the guy on the payphone behind Adam. The guy is giving him instructions.
Revealing mistake: When Rob is in the Cafeteria eating all the coleslaw, he yells "I'm the coleslaw king of the world!" there is a girl in the background who mouths it as he is saying it. (00:50:00)
Revealing mistake: In the David Letterman scenes, Paul Schaeffer's head is shaved, which he just did recently (maybe within the last year to year and a half). (01:15:00)
Revealing mistake: In the scene where Joey parks his car behind Kat's you hear him coming up really fast and then you see it stop, but if you look in the window across the street you can see in the reflection that the car was still and then it just moves up a little bit. (00:25:30)
Revealing mistake: At the party where Inspector Gadget lights a cigar for Scolex, he uses his thumb which flips open to reveal a flame. When they cut to the close-up of Scolex getting the cigar lit, you can see that there is a hand holding up a traditional lighter, and not Inspector Gadget's thumb any more.
Revealing mistake: During the catamaran sailing scene, the boat jibes and Brosnan leaps across the trampoline and starts grinding on an empty winch, with no line in it. (00:37:40)
Revealing mistake: When all four of the guys are driving the Volvo through Detroit, if you watch real close, sometimes you can see 1980's and 90's vehicles parked on the side of the roads. Especially when they show a long shot with an older mustang following them, there is what looks like (it's hard to tell) a newer Buick or Chrysler (like the 300m) on the left side of the screen.
Revealing mistake: During the prom scene, especially during the song "(Don't You) Forget About Me", none of the band guys (especially the older man keyboard player) are actually playing their instruments.
Revealing mistake: In the scene where they are all having a farewell dinner at Tony's restaurant. At the end of the meal they are all scattered around the restaurant, the camera is on Bella and Honey and in the background, outside the restaurant, 4 extras walk past, 3 at the front and one behind. The next shot is at the window where Max and William are sat, again the 4 extras walk past in exactly the same order and positions. They are the same people because one of them has a pink top on and you see that twice.