Revealing mistake: A live bull is lowered in a sling to feed the raptors in the pen, but when the shredded sling is brought back up, there's no blood on it. How could they have shredded the sling without drawing blood on the bull?
Revealing mistake: When Nedry is attacked by the Dilophosaurus, (the spitting dinosaur), the first spit supposedly lands on his shirt, BUT if you look closely, Nedry slaps it there himself with his hand - there's only a little bit on his shirt before he hits himself, then there's loads.
Revealing mistake: During the scene where Dr. Grant and the children are forced to climb a fence to flee from an unseen dino, there's a brief side view of the fence that clearly shows that it isn't continuous - it is probably only about 75 feet wide.
Revealing mistake: When Grant is trying to save the two grandchildren in the over-turned Jeep, the T-Rex returns and surprises them. Grant holds the girl and tells her not to move. The Rex then starts smelling around and blows Grant's hat off. Well if you watch closely, you can see that the air that blows Grant's hat off doesn't come from the T-Rex, it comes from something under the Rex.
Revealing mistake: When the T-rex is attacking the jeep and he has turned it over, the camera pans round behind the T-rex and you see through its legs, the ground all around the base of the beast is DRY but it's been pouring with rain for a while.
Revealing mistake: When Lex and Tim are playing hide and seek with the Raptors in the kitchen, when the camera cuts to a wide shot of the Raptors walking in from a distance, the Raptor on the left looks directly at Tim while he crawls by, but then looks back in the direction it was going.
Revealing mistake: When Grant and the children are up in the tree, as Tim is telling his jokes the camera pans out and we get a wider view. In this shot you can see that Grant's boots are spotlessly clean, which is highly unlikely given the muddy ground, wet environment and his activities over the past few hours.
Revealing mistake: When Nedry is getting eaten by the spitter dinosaur, if you look down at the bottom of the Jeep, you can see the lights reflecting off of the camera lens.
Revealing mistake: When Alan and Lex are holding on to the cable, fearful of the Explorer that is about to come tumbling down at them, you'll notice that the car, if it had been filmed at the same time the actors where there, would have cut off Sam Neill's leg. Lex grabbed the wire in time but Sam doesn't move his leg enough.
Revealing mistake: The T-rex does not leave or make any footprints in the soft mud during the attack on the car.
Revealing mistake: When Grant tells Lex and Tim about the breeding he then gestures to the dinosaurs' footprints. Some of the footprints are very square in shape and have obviously been stamped in the ground.
Revealing mistake: When the Dilophosaurus spits at Nedry, you can see the smoke from the gun used to shoot the spit in his face, top left of screen.
Revealing mistake: When Ellie runs from the Raptor the stunt double who runs for her has on a wig that looks nothing like her real hair. It just looks very fake.