Revealing mistake: When the car at the end flips over, you can see a circular object underneath the vehicle, about the size of a tyre (very obvious in slow motion). This is the device that "lifts" the vehicle for it to flip on one side, timed with the appropriate explosion.
Revealing mistake: When the blond lady dies, she is seen in a body bag. Look at her nostrils as they widen, revealing that she is not quite dead.
Revealing mistake: In the scene in the toilet where Chip (Jim Carrey) beats up Robin's date (Owen Wilson), you can see throughout the whole of the fight that Owen Wilson is either laughing, or trying not to laugh.
Revealing mistake: When Jamie and Sandra are arguing and rolling about on the floor in their lounge, the microphone powerpack on Jamie's back is visible through his t-shirt. (00:32:05)
Revealing mistake: When Martha is in her office and the phone rings, when the camera shows the phone, no line is lighting up, yet when she picks up the phone everything is normal and the phone conversation starts. Having owned one of these phones, first of all since they are multi-line phones when a light is flashing green that means an incoming call and a solid red means a line is being used but none of this stuff shows up in the scene. Second of all, the secretary earlier on in the movie says she has a call on line two, therefore proving she has more than one line on the phone.
Revealing mistake: When Hawkins is pulled into the lifeboat by Long John Silver, if you look closely, you will see that it is a stunt double who is doing the falling.
Revealing mistake: In the scene at the end of the movie when the detective is listening to the Senator's confession on tape, there are no speakers attached to the stereo.
Revealing mistake: When Joe is beat up the second time when he just gets off of the bus in NYC, during the simulated punches his head hits a sheet of Plexiglas. The makeup from his forehead leaves a tan stain on the Plexiglas.
Revealing mistake: On their wedding night Rose and Greg watch 'Lawrence of Arabia' on video, lying in their separate beds. When the movie is over Rose comes and switches the TV off, but before she does that you see a reflection of her in the TV where she is standing there and waiting for her 'turn'. (01:02:35)
Revealing mistake: Certain parts of this film were made during the spring months, not winter. In the background of the high up shots during the parade, leaves can be seen on trees (in the distance). Also, the grass is surprisingly very green, in several locations.
Revealing mistake: When Doug 2 wakes up and sees Doug 1, Michael Keaton's body double is noticeable in the angle shot from behind - he has bulkier hair.
Revealing mistake: When Buddy throws Reggie at the piano, you can see it's his stunt double instead of Buddy.
Revealing mistake: When Sassy comes out of the burning house carrying the kitten in her mouth you can tell that the kitten is fake.
Revealing mistake: During the scene with Patricia Arquette sitting on the hotel toilet in her robe, she reaches for the toilet paper and spreads her legs for a moment. We can see she is wearing panties while she was supposedly doing her business.
Revealing mistake: When the Leprechaun gets sucked into space, he grabs onto the edges of the cargo bay's doors. You can see pieces of his hands disappear into the doors, showing that it's CG.