Deliberate mistake: At the end of the film when Pacino and the gangsters are shooting each other on the escalator, the escalator takes a long time to get to the bottom, way too long.
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: At the end of the film its revealed all the murders were a hoax and everyone was in on the plan to set up Rex (Lee Majors). Why then exactly were Rachel (Vanessa Angel) and Patrice (Adrian Paul) talking together and pretending like they were trying to find the killer. In one of the scenes Rachel believes she has caught a photo of one of the men who she thought might be a killer and is showing Patrice, but Rex wasn't anywhere around. Therefore why were they pretending to find a killer or keep up the illusion whilst Rex wasn't around?
Deliberate mistake: The dummies are obvious when the jail bus is flipping over onto the railroad tracks.
Deliberate mistake: Gray's rental car just happens to be the one car out of the hundreds in the parking garage that the bad guy chasing Gray and Darby crashes into, setting off the bomb he had placed.
Deliberate mistake: It's meant to be a joke, but the way the famous punch scene happens is completely ludicrous. Darian appears to be flying in the air toward Nick to attack him, but there is no explanation of how she is doing this, and the way she was thrown back high in the air a few feet is something a punch can never do unless with inhuman strength. There's not any reason whatsoever that both of these things happen, except to give the viewers a laugh. A gun in this case would have made a whole lot more sense.