Revealing: When Jack is hanging out of the truck you can see him standing on the hood of the car which Lydia is driving. At some points we get camera view from the back seat of the car. In some angles the mirror inside the car disappear. This is to prevent us from seeing the camera.
Great sites
Trivia
After Scrimshaw and Canker are shrunk 50%, there are a few scenes where they are seen with full-size actors. These shots were actually filmed using forced perspective. For the car scene, the rear of the car is actually twice as large as a normal car rear, and was about 20 feet away. During the scene half size hands and double-size heads were used. Using this method, the film-makers didn't have to worry about compositing two separate shots in post production, so the shots could be completed quicker. Even in the final scene with the suitcase, the case was twice as large, but the hand that closes it was real, closer to the camera in sync with the closing. (It took about 20 takes before it was perfect). See more...
Continuity: In the beginning, after Dennis Quaid has been beaten up, the pins on his jacket are pinned, then hanging askew, then pinned again.
Continuity: When Jack is having a seizure at his job he stuff some aspirin in his mouth. When the manager says "He is spaced out." it cuts to the girl saying "I'll handle this.". At that point Jack has got two aspirin hanging out of his mouth. It cuts and the aspirins are gone.
Visible crew/equipment: After The Cowboy has put out his cigar in his hand he flips through a magazine. At two points you can see the protective item he's got in his hand to avoid getting burned by the cigar.
Continuity: Inside the truck when Jack is freezing his head is shaking. But from Tuck's view, inside Jack, he is not shaking at all.
Continuity: Just after the scene where Jack Putter gets tazed by Lydia Maxwell in the restaurant, Mr. Igoe initially hauls the unconscious Putter over his left shoulder. In the following shot you'll notice that when he exits through the back door, he's carrying Putter over the right shoulder. This mistake was pointed out by the director (Joe Dante) himself on the commentary track of the DVD version.
Continuity: We see Jack looking in a mirror in order to show himself to Tuck, but when he turns away, the picture on Tuck's monitor is still focused on the mirror.
Continuity: In a scene right before Jack jumps into the car from the truck we can see Lydia grab the back of his ankle. When it cuts the way she holds his ankle changes.
Revealing: When Martin Short is escaping the lab in Dennis Quaid's car, Dennis says that it is a 5-speed manual transmission. Immediately after this you can hear the car very smoothly shift up gears but Martin's hands haven't left the steering wheel.
You may also like: Three Men and a Baby | Sands of Iwo Jima | The Sandlot | Stand By Me | Sixteen Candles