Revealing mistake: When Carl is caddying for the priest during the bad weather, the wind is so strong that it is almost blowing them over but the trees are not moving in the background.
Revealing mistake: In the dance sequence, we see Elaine twirling Ted around and throwing him into the crowd. Watch the top-right-corner of your screen, as the stunt-double lands in the audience you can see Robert Hays (Ted Striker) in the top-right-corner waiting to pop out. (00:19:10)
Revealing mistake: When the sheriff's car is flipped upside down, the sign behind the car is upside down too, so you can tell the car isn't really upside down.
Revealing mistake: When Jake and Elwood are driving through the mall, they leave by driving through some store, if you watch as the people run to get out of the way, a black man with an apron on runs right into the camera. (00:31:40)
Revealing mistake: When Laura tears the piece of paper with the LAX clue on it, you can see the paper crease so she will have a straight tear.
Revealing mistake: It's obvious that when Clyde disassembles the car, the car has been pre-disassembled so Clyde would have an easy time taking it apart. Specifically the doors and trunk lid.
Revealing mistake: Gutchel brings in the sewers the animal carcasses using the supermarket cart. He gets inside, then passes a first tunnel, then another one...or rather, passes the exact same tunnel as before, but in the other direction, to make it look like he travelled a bigger length - just check the graffiti on the wall, it's the same one. (00:09:25)
Revealing mistake: After the shot that shows Herbie spitting sea water from his exhausts, look at the bumper in the next shot of Herbie, when he gets black smoke from his exhausts. The rust doesn't look real, because they used paint to make it look like rust.
Revealing mistake: A helpful guy is holding a jar supposedly holding the fish that were recovered after the tank was cracked open by the shot. You can tell however that there's no fish in it and Susan Saint James is dropping a handful of nothing in it. (00:21:00)
Revealing mistake: Linderman refuses Clifford's offer to be his personal bodyguard from Moody's gang, and leaves. As Clifford walks by the students practicing their violins, playing Mozart, their bow movements do not match the music.
Revealing mistake: When the private eyes are outside on the grounds there is loud thunder and lightning but it never rains.
Revealing mistake: During the fight, Popeye ducks Oxheart's swings. If you watch carefully, it appears to be the same swing repeated multiple times from different angles.
Revealing mistake: When Terrible Tommy has Rosa in an airplane spin her hair suddenly gets thicker and her legs get thicker, indicating this is Rosa's stunt double.