Character mistake: When Genarro is explaining to Hammond that he is at the park to report Hammond's progress to the investors, he says "In 48 hours if they're not impressed, I'm not impressed. We'll shut you down, John." He should have said "If I'm not impressed, they're not impressed" since the investors would be shutting down the park on his advice, not the other way around.BaconIsMyBFF
Continuity mistake: In the tree, before Lex tries to feed the dinosaur there are no branches or leaves in front of her. She leans forward and a shot later a branch filled with leaves has magically appeared by her waist in a mere nanosecond. This keeps changing back and forth depending on the angle.Sacha
Continuity mistake: After Hammond says "Welcome to Jurassic Park" Grant is facing the jeeps, 3 meters away, with Ellie 5 meters to his right and Hammond 3 meters to his left. Grant then turns his waist around to the left, though his legs still face the jeeps. In the wide angle everyone has changed positions drastically: Grant's legs have magically turned 180° and Hammond is not only opposite Ellie but very close to her.Sacha
Continuity mistake: Ian gets out of the car to distract the dinosaur. Inside the car, he's nice and dry, but the second he gets out of the car, he looks like he's stood in a bathroom shower for ten minutes.
Continuity mistake: When Nedry's car is stuck in the mud, he goes out front to grab his winch and pulls out a fair bit of wire. In the next shot, we see that he has a lot less wire than before, even though we never heard the winch retract.
Factual error: At the beginning of the film we are shown an amber mine in the Dominican Republic. This amber is only 45 million years old, Hammond would never bother buying the amber from there as dinosaurs disappeared from the fossil record 65 million years ago.