Continuity mistake: Before the vehicles leave the compound Lex says to Grant, "She said I should ride with you cuz it'll be good for you." In this shot, Ellie's door on the second car is open with Malcolm talking to her. In the next close-up shot of her, the door is closed with Malcolm gone.
Revealing mistake: In the sequence when Lex almost falls from the hole in the ceiling, she looks straight back up at the camera. Rather than cut away from the stunt double at this point, they actually bothered to CGI the actress' face over the top so they could use the sequence right through. Unfortunately you can tell what's been done.
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 explorers break down outside the T-Rex paddock, Grant can be seen filling a flask with rainwater out of the door. When the angle changes the door is closed, then the angle changes again and he is still collecting rainwater with the door open (fixed in the VHS Widescreen and "Ultimate Collection" DVD box set versions).
Continuity mistake: After Gennaro runs off to hide in the restroom there's a shot of the fence cables ripping apart, and in the following shot of the back of one of the Explorers note that it's missing its black roof vent (and rear wiper), but in following shots of Explorers 4 and 5 the vents are intact on both vehicles. Then just as the T. Rex starts pushing Explorer 4 upside-down its roof vent is gone (presumably, the vehicle missing the vent is a stunt vehicle).
Add timeSuper Grover
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.