Factual error: The predator enters the compound and picks up the scorpion. The silhouette of the scorpion changes from bright to dark, showing a drop in temperature. But scorpions are cold blooded animals who have an ambient temperature. The predator should never have seen it at all.
Factual error: Ventura carried the M134 Minigun and an ammo pack which holds 500 rounds. At its firing rate, that ammo would be spent within a matter of seconds, not minutes as was seen in the movie. (00:47:45)
Factual error: The heat from Dutch's body would warm the mud up in a matter of seconds (tested by the Mythbusters). It doesn't even cover all of his skin or his eyes. And the Predator isn't filtering his input for only large heat sources. His normal vision tracks in on a rat hiding just above Dutch.
Factual error: In the scene where Dutch is making his improvised explosive arrows we get a close up of him dismantling a 40 mm High explosive grenade and dumping the propellant out onto a large leaf. Way to much powder came out. An actual 40 mm has only about an amount equal to a sewing thimble full.