Revealing mistake: Near the beginning of the film, when Charlie and Brian steal the Honda there is a shot where Brian says "Charlie, slow down, think". By comparing the view outside of the car window in this shot to the surroundings of the previous and subsequent shots, we can see that it was filmed out of sequence, and in a different part of the parking lot.
Revealing mistake: Throughout the car chase, the same white Plymouth Volare coupe is seen over and over, sometimes parked, sometimes being passed going in the same direction, coming head-on, or getting bumped out of the way.
Revealing mistake: Our hero Sherman is talking to Maria's husband, and right after he tells a story he coughs and falls on the table dead. The thing is, he falls with his mouth open, but as he lays there on the table he closes his mouth.
Revealing mistake: At the start of the film, where West and Cain are re-animating dead soldiers, one of them tries to kill West. So, he shoots him in the head. It's obvious that West's gun doesn't fire, and the soldier just pretends like he's been shot.
Revealing mistake: When the car crashes into the tall display of tennis balls in the store, there's a dummy on top of the car dressed up in the same clothing as Ben.
Revealing mistake: After the guy gets killed in the alley, he lifts his arm to allow the other guy to drag him away.
Revealing mistake: The bottom of Tony's legs disappear when Elliot emerges from the phone and grabs hold of him.
Revealing mistake: When Webby and the others are standing outside of the window watching Scrooge pace back and forth in anger, she casts no shadow on the patio. This is revealed when she moves left at one point. (00:28:50)