Continuity mistake: In an early scene, Samuel L Jackson's character is struggling to get the computers up, and he is smoking away. A full cigarette, then half, then full, all without lighting a new smoke. (00:56:25)
Continuity mistake: The satchel of money Nedry receives as a down payment for getting the embryos off the island vanishes from his arms as he looks at the false container of shaving cream. It vanishes mid-sentence; he had no time to put it down. (00:14:00)
Visible crew/equipment: When the two Explorer vehicles begin the tour and drive past the huge automated wood doors, if we look at the area between the two doors just as the doors are shut we can see someone's arm come down from behind the door on the right, presumably to keep both doors properly closed for the shot.
Visible crew/equipment: In the kitchen scene, when the raptor appears in the small window. You can see movement (possibly a reflection of a camera person's arm) on the surface of the door, right below the window. (01:43:45)
Revealing mistake: While the T. Rex attacks the Explorer that Lex and Tim are in, during the stunt as the acrylic glass roof comes down on the kids in the interior shots, the strip of duct tape falls through the opening and dangles from the roof of the vehicle - presumably the tape was holding the acrylic glass roof in place before the stunt.
Continuity mistake: When the T. Rex escapes its paddock and then Tim tells Lex to turn the light off, in the interior shot after Tim closes the vehicle's door, the plastic piece (used for seat belts) anchored to the panel between the windows vanishes inexplicably leaving just a hole, and when the T. Rex roars Tim covers his ears and there's some kind of small plastic on that hole.
Continuity mistake: After Alan pulls Lex out from the overturned Explorer and the T. Rex spins the vehicle around, in the closeup shot from behind Tim while he's still inside the Explorer, as the T. Rex leans down facing Tim we can see one of the lower front teeth is missing, but it's back in the following shots.
Continuity mistake: In the Badlands scene, when Dr. Grant enters the trailer there is a large overhead shade blocking out direct sunlight. On the inside light is streaming through the windows. On top of that, the first window is larger when seen inside the trailer than it is when seen from the outside. (00:09:50)
Continuity mistake: When Tim, Lex and Dr. Grant are hiding in a large tree, a large dinosaur appears. They pull some branches off the tree and feed the dinosaur. However, when they first climb the tree, there is no foliage in the area at all. (01:19:20)
Continuity mistake: When the two kids are eating the food just before the raptors try to attack them, the little boy's hair is all messy and strands of it are sticking out. In the next scene, when the kids run into the kitchen and hide behind the counter, his hair is perfectly straight and combed. (01:43:30)
Factual error: In the early scene where Dennis Nedry meets a man to plan the embryo theft, the subtitle says that they are in San José, Costa Rica. However, the sleepy coastal town in the movie within sight of the ocean bears no resemblance to the real San José (a cosmopolitan capital of almost 1 million people, situated 50 miles from either coast). Even the book makes this error. (00:13:10 - 00:14:45)
Visible crew/equipment: In the scene where Grant and Lex are hanging from the fence cables on the wall in the Tyrannosaur paddock they start swinging back and forth to avoid the truck that is about to fall on them. Look closely in some of the closeup shots, you can see that the cable that Grant is holding on is actually a safety rig. The harness straps are visible.
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 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)