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)
Continuity mistake: When Tim and Lex first arrive, Lex is wearing a purple tank top with a colorful design, and in the following scenes or even between consecutive shots her tank top changes to completely different designs, though it's the same style of tank top.
Continuity mistake: After the T. Rex rolls Explorer 4 upside-down with Lex and Tim inside, in the closeup when the dinosaur bites on the rubber tire we see the hub hole at the center of the wheel rim, but two shots later the wheel cover is back on the wheel.
Continuity mistake: While Lex and Tim are hiding in the kitchen, when the large serving spoon falls it cuts to the closeup of the two Velociraptors and the tall shelving unit has vanished, but in the next shot when the one of the raptors leaps onto the counter that tall shelving unit is back.
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).
Continuity mistake: When Ellie and Muldoon rescue Ian they leave him in Jeep 10 while they go looking for Alan and the kids, and after the closeup of the water filled T. Rex footprint showing an impact tremor, the next shot zooms in on Ian and we can see the driver's side-view mirror has no writing on it. When they're being chased by the T. Rex, in the shots from behind the Jeep we can see that both side-view mirrors have writing at the top and bottom (shown in closeup "objects in mirror are closer than they appear").
Continuity mistake: While Lex and Tim are hiding in the kitchen, just as the Velociraptors come in Lex tells Tim to follow her, and when they turn into the aisle there's a stainless prep unit with no open shelves right beside them at the end of that aisle, but after the closeups of the Raptor's claws, when the kids continue to crawl away that prep unit has oddly vanished - the last unit in that aisle has shelves, and then it reappears when Tim sits under the utensils.
Continuity mistake: When both Explorer vehicles are parked at the paddock, in the shot of the goat being raised to lure the T. Rex, the "No! Feeding..." sign is permanently affixed to the front of the concrete wall, but in the previous and following shots that same sign is affixed to the angled top part of the wall. Later, when the power goes out, that sign is once again affixed to the front of the concrete wall.
Continuity mistake: After Hammond's chopper lands causing winds at the dig site in the badlands, when Alan opens the trailer door the rock hammer is hanging from his belt, but in the interior shot as he walks in the rock hammer has vanished.
Continuity mistake: After Dennis has stolen the embryos, when he reaches the first gate he gets out of the Jeep then uses the manual override to unlock the gate, and in the exterior shot when Dennis walks back to the Jeep his door is wide open, but in the next interior shot his door's closed and he even has difficulty opening it.
Continuity mistake: In the scene with the T. Rex breaking through the glass roof, as the glass breaks one of the rex's front teeth breaks off and flies backward. On the next close-up of the dinosaur's mouth, the tooth is still missing, yet it is back in all shots after that.
Continuity mistake: Right before the T. Rex breaks out of the paddock there's a shot of the back of Explorer 4, and the rear windshield wiper is gone, but it reappears, vanishes, and then reappears again during the T. Rex attack.
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: 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.
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: At the site of the T-Rex attack, Ellie and Muldoon help the injured Dr. Malcolm into the back of the Jeep, before Ellie goes looking for the other Explorer. Muldoon hears the T-Rex approaching and shouts "Ellie, come on!" but Ellie spots the Explorer over the wall and (in the next shot) she and Muldoon (heard but unseen except for his torch beam) have left Dr. Malcolm alone, somehow descended the high wall, and are running up to the wrecked Explorer. There is no implied time gap between the shots as they could hear the T-Rex was approaching before they did (or did not) descend the wall and later the T-Rex is almost at the Jeep (now in a different location) and Dr. Malcolm is urgently calling them back.
Continuity mistake: When the T-rex is attacking the kids in the car, in the shot where it stands on top of the car, the metal begins to buckle in the next shot inside the car. When it starts to sink, the metal isn't buckled and you can see the car sinking into the mud pit.
Continuity mistake: When the car with Timmy in it falls down the wall, it lands in a tree flat again the concrete wall. Yet later when Alan is rescuing Tim, this is no wall to be seen anywhere. Only other nearby trees.
Continuity mistake: When the tyrannosaurus is crushing the upside down Landcruiser and mud begins to flow in through the side shattered windows, Lex and Tim are already completely muddy all the way from the tops of their heads, possibly from previous takes.
Chosen answer: They all left on the same boat Nedry was trying to get on with the embryos. You can hear Samuel L Jackson's character announce that the boat will be leaving at a specific time and everyone had to be there or be left behind.
Shannon Jackson