Deliberate mistake: Just before Danny enters the action movie, Jack Slater (Arnold) arrives at his 2nd cousin's house. Jack exits his car and jams his desert eagle pistol into his waistband. He then approaches the front door where he turns toward the camera to kick in the door. You can clearly see there is no gun in his waistband now. In the next shot he draws the gun from his waist. (00:22:50)
Deliberate mistake: When the raptor breaks into the control room and is hopping around the computer workstations, we see sharp, distinct genetic coding projected from a computer screen and across the raptor's face (starting 1:55:50). Aside from the fact that computer displays have never projected focused images onto nearby surfaces, the projected text shown in this scene oddly reads from left-to-right, when it should actually be a flipped mirror-image (right-to-left). Spielberg probably realised this factual incongruity while filming but chose to use the left-to-right text for the sake of audience recognition, given that the multiple lines of "GATC" genetic code were already confusing enough. (01:55:50)
Deliberate mistake: The dummies are obvious when the jail bus is flipping over onto the railroad tracks.
Deliberate mistake: When Wyatt comes out of the Oriental and joins his brothers in the street to tell them he's acquired a quarter interest in a game, a herd of cattle is passing them in the street but there's no dust kicked up by the cattle, when in reality there would be a lot of dust on a dry desert street in Arizona.