Continuity mistake: When Nedry opens the first gate, the big one that the explorers entered, the jeep he is driving has a long, thin antenna on it that is waving about, and is standing up straight. At the next gate, it is tied down, and looks semicircular. Nedry wouldn't have spent time tying it down since he had to get to the docks. (00:56:00)

Revealing mistake: When the T-Rex flips the Explorer over, as it settles on its roof, the stunt control wires are visible at the rear of the vehicle. This mistake was corrected on blu-ray. (01:03:40)
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. (01:45:15)
Revealing mistake: When Grant is trying to save the two grandchildren in the over-turned Explorer, 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. (01:05:35)
Continuity mistake: During the opening sequence a couple shots show it raining where other shots have no rain and a dry environment. First noticed after Muldoon says "Jophery raise the gate" and when the gatekeeper falls off the transport box. (00:02:10 - 00:03:20)
Visible crew/equipment: 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. (01:10:35)

Continuity mistake: When they first land on the island, the actors' positions change. In the interior shots, Satler is sitting to Hammond's left during the descent. When the copter door opens, Hammond is on the other side, his left side facing the door. They would not have switched places during the descent. (00:16:55 - 00:17:45)
Visible crew/equipment: When Hammond and Muldoon enter the control room with the weather report look to the right of the door. The dark camera is visible in the reflection and it moves away as they walk by. (00:38:50)

Revealing mistake: When Tim is shocked off the fence as the power comes back on, the sparking effects are not where his hands are touching, instead the sparks are several inches away. (01:39:00)
Continuity mistake: When entering the visitor centre, Ian goes from the side of Hammond to the back of all the characters without a chance to move, in a single shot.

Revealing mistake: When the T-rex is attacking the vehicle 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. (01:05:45)

Continuity mistake: When Grant and Malcolm's car suddenly "just stops" you can see outside that they are in a thick dense jungle area. A few minutes later, the two parked cars are in a wide open area next to the T-Rex fence. (00:55:20 - 00:58:10)
Visible crew/equipment: When Tim is following Grant before they start the vehicle tour,Tim sits in the first car.Look to the right of the door frame and you will see a dark shadow get larger.This is obviously the camera.When Grant finally shuts the door the large shadow is even more visible. (00:38:00)
Continuity mistake: Near the beginning, when the helicopter lands on the island, the Jeeps are already waiting in position. In the next shot they reverse up to the helicopters again. (00:17:20)

Continuity mistake: In the opening scene Jophery is being attacked by the dinosaur in the cage and Muldoon is holding onto him while the workers shock the dinosaur. Muldoon's hat is on in one shot, then the camera cuts and it is off while the camera is dollying forward, then it is on again. This happens just as he is about to shout "SHOOT HER! SHOOT HER!" (00:03:00)

Other 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. (01:20:35)

Continuity mistake: When Grant grabs onto the electric fence, his hands are a short distance apart and there is a set of vertically positioned wiring in between his hands - the warning sign is also barely covering the "hole" in the wires. A couple of shots later, without letting go of the fence, his hands are much further apart and there are now three sets of vertically positioned wiring in between his hands. The angle of the wires also changes, and the sign is now well into the "hole", very near his hand.

Continuity mistake: In the opening sequence, just after Jophery has been grabbed by the Velociraptor, he gets dragged up in the air. Muldoon reaches up for him then, in the next shot, he reaches up for him again. (00:02:55)

Continuity mistake: When they are on the dinosaur's bones, one of the cords attached to the section that Lex is on comes out. The bone starts to fall and (for a fraction of a second) you can see that Lex lets go of it but in the next shot she is hanging on again. (01:51:45)
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. (01:06:45)
Chosen answer: Yes. The first opening day of Disneyland in California was catastrophic. The pavement was fresh and the sun was so hot high-heeled shoes actually sunk into the walkways. Counterfeit tickets were made, resulting in more people than the park had room for. They ran out of food and drinks. Bathrooms clogged and shut down. Many of the rides broke down on opening day. The Storybook Land Canal Boats had to be pulled by cast members in rubber boots. At the time, there were no guide rails for Autopia; some of the cars crashed into each other, making them inoperable. A gas leak in Fantasyland lead to the land being temporarily closed for part of the day.
David Yard