Factual error: When Brendan Fraser & his son are running to reach the pyramid before the sun hits it, the sunrise line approaches the pyramid along the ground, but the sun would naturally have hit the pyramid at the top first and worked its way down to the ground. [Some people insist on trying to correct this - think of it this way. If the sun's illuminating the ground from way up in the sky, what's keeping something higher up than the ground in darkness?] (01:34:40)
Factual error: There is no way a 2001 phone's tiny speaker could be heard a hundred meters away in the belly of a dinosaur or later buried in a mound of dino dung.
Factual error: When the kids are getting hit from behind by the truck, cut to a side shot of them in the car, the boy's body moves forward, while the girl's body is more properly propelled in a backward motion relative to the car. This happens several times.
Factual error: Towards the end of the movie, Mary sends a hand-written note to Inspector Abberline. The 'r' in her name is written in a North American style, where she is European.
Factual error: Ruthie gets impaled on a jagged shard of glass from a modern shower door, but shower doors are made of safety glass (since 1977) - when they break they don't leave sharp knife-like shards, only tiny pieces.
Factual error: When Grace goes into the children's bedroom to wake them up to introduce them to the new nanny and maid, she takes the only lamp they had with her into the bedroom but light is still reflecting off the nanny and maid as if a lamp was still there. (00:08:20)
Factual error: When Mike first starts listening to the session tapes, the camera does a slow pan down the label on the box. Quite clearly, we can see that the patient's diagnosis is listed as "D.I.D.", along with a few names. Since the hospital closed in the mid 80's, it is not possible for her to have that diagnosis. Before the early 1990's, D.I.D. (Dissociative Identity Disorder) was known as M.P.D. (Multiple Personality Disorder). In later scenes it is correctly listed in the woman's files as Multiple Personality.
Factual error: When they get to western Nebraska, there are several scenes showing a mountain range in the background. There are no mountains anywhere in Nebraska.
Factual error: Burt claims his watch updates its time "by connecting directly to the cesium clock in Colorado via ultrasonic frequency." Later the graboids home in on him by the ultrasonic sound emitted by his watch. Firstly, radio controlled watches update their time by receiving signals, but they don't emit any signals - the battery would be way too weak for two-way communication. Secondly, they work on radio waves, not sonic waves. Thirdly, if a hypothetical time transmitter did work on ultrasonics, the smallest distance between Colorado and Nevada is some 435 km (around 270 mi). An ultrasonic signal strong enough to reach that far would probably be deadly within a sizable range around the transmitter. (00:08:20)