Visible crew/equipment: In the scene where the cow is being lowered into the raptor cage, the camera shows the ferns and plants shaking. If you look closely, there is the back of a man in a white shirt shaking the plants.
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.
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.
Revealing mistake: When the Explorers are entering the park through the large wooden gate, during the overhead angle you can see that the perimeter fence isn't continuous.
Revealing mistake: In the shot immediately following Ellie turning on the circuit breakers when the raptor attacks her, we see a light bulb touching its head. There is smoke appearing where the bulb is in contact with the raptors head, the power has been off for a while the bulb would not be that hot after being on for just a few seconds.
Continuity mistake: Hammond pours champagne into his glass and it's full of foam. After Grant says his line, when Hammond says, "...for the next three years." the foam is all gone. Foam from champagne takes longer to disappear.
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 Jose, Costa Rica. However, the sleepy coastal town in the movie bears no resemblance to the real San Jose (a cosmopolitan capital of almost 1 million people, situated 50 miles from either coast).
Continuity mistake: When the T-Rex has come and nearly destroyed the car, Grant is trying to get Tim and Lex out of the car. Lex then screams and this causes Grant to turn around and cover her mouth. They are sitting on one side of a tyre on the car when Grant has his hat on. In the next shot (when the T-Rex has blown Grant's hat off) they are on the other side of the tyre.
Continuity mistake: Just as they start going down the wire into the T-Rex paddock, in addition to the problem mentioned above with the ground level suddenly dropping, take a look at the wire. In the first shot underneath them it's curling up and towards the camera, like it's caught on something, then it changes angle, and the wire's hanging straight down.
Continuity mistake: When Dennis tries to get the dinosaur to fetch a stick, at first the stick is perfectly straight. Then they show a shot of Dennis from the front, and all of a sudden the stick is crooked.
Continuity mistake: Right before Lex and Tim scream when the T-Rex roars at them Lex is holding a flashlight, in the first shot you can see that Lex is staying completely still with the flashlight facing towards the driver seat but in the next shot you can see that it is pointing out the passenger side window.
Continuity mistake: When the group are at the velociraptor paddock Hammond says "And that's why we're taking extreme precautions". Dr. Malcolm's head changes from looking sideways to being tilted down a lot more. Also Hammond starts to turn and then turns again in the following shot.
Continuity mistake: After being electrocuted, Tim flies down vertically, but Dr. Grant catches him horizontally.
Continuity mistake: When Nedry is trying out the shaving foam can, he puts some on his right hand. When the camera pans back after he's wiped most of it off on the pie, his hand is suddenly completely clean. He then pretends to wipe it off with a napkin anyway.
Continuity mistake: When the T-rex is attacking the vehicle with the kids inside, Alan gets out of the other car. Even though it is pouring rain and Alan is standing perfectly still, no raindrops are seen hitting his solid, medium-colored shirt. It stays perfectly dry, even though there is nothing overhead that is shielding him from the rain. It is only after the scene cuts to him at the other car that the shirt is suddenly drenched. The rain is obviously CGI.
Revealing mistake: When Alan and Tim climb down the tree to escape from the falling car, you can see cables along the bark of the tree below the car as it falls.