Revealing mistake: When Billy cuts his chest before facing the predator, it's obvious that there's a blood tube on the back of the blade. The blood gets "spread" onto his chest like butter on toast whereas in reality a cut forms and then blood beads out and flows moments later.
Visible crew/equipment: When Arnie says 'oh s***' and falls off the cliff, watch as the camera goes over the edge. If you look on the mountain, you can see a shadow of a black ball with a cable attached: this is the camera filming the shot which has been thrown off the cliff.
Continuity mistake: After Dutch has defeated the Predator, right before the 'What the hell are you?' exchange, the Predator spits some neon blood onto its face which immediately disappears.
Continuity mistake: When Dutch (Arnold) has been shot in the arm by the Predator, the wound changes between shots.
Continuity mistake: When Arnold had his face in the mud after swimming to shore to escape the predator, He looks back at the predator and his face is 1/2 covered with mud. The scene's after this his whole face and is covered.
Visible crew/equipment: Watch when Arnie is sliding down the cliff: it shows a shot from his eyes looking down at his feet, and you can see the wooden platform he's sliding down.
Continuity mistake: In the first 20 minutes the camouflage on Dutch's face keeps changing between shots - black stripes on his forehead keep changing and then green stripes are added later in continuing scenes.
Revealing mistake: When Dillon and Anna are arguing in the terrorists hideout near the burnt out helicopter, the corpse on the ground behind them moves his foot.
Revealing mistake: While the Predator is healing himself with his surgical material, the marks of the brands are visible.
Revealing mistake: While Dutch is struggling with the Predator in the jungle, in several shots the stuntman is visible.
Other mistake: The time of the chopper arrival for rescue (after the village attack) is said to be 09:30 but the voice on the radio says 10:30.
Suggested correction: Maybe the pick-up time changed. When Dillon (Red Fox) calls Blazer One for extraction (after the village fight and Blane's death), he's told "next contact 9:30." Dillon confirms pick-up at 10:30 hours.
Continuity mistake: In the last helicopter scene the General's rank changes from 1 star on his hat to 2 stars on his collar.
Continuity mistake: Early in the movie, Mac throws the dead green berets' dog tags to Dutch. As he catches them, Dutch has his hand closed in a fist, and the dog tags are hanging to the left. But in the close-up shot where we can read the name, his fingers are more open, with the tags resting in his palm.
Revealing mistake: Blaine is dead in the body bag, but when Mac puts the flask on his neck, you see his pulse.
Plot hole: After Blaine gets killed and the group hose down the forest, Poncho goes and checks for the enemy. He comes back and says he didn't find tracks or blood "We hit NOTHINGGG." Now, while he would be looking for red blood, he certainly should have noticed at least the glowing Predator blood (made from glow stick fluid - widely used by the military and public alike at the time) easily visible on the large leaf, and deduced that came from something - perhaps the enemy soldier had a glow stick.
Suggested correction: This isn't a plot hole. The plot of the movie isn't broken because of this. It's an assumption that he "should have noticed" the predator blood but he might not have. And if he had, and had discounted it, it would only be a character error not to have mentioned it.
A plot hole doesn't strictly need to "break" the plot to count as a plot hole. The term most often refers to instances when a film contradicts its own sense of internal logic. For example, something happening that contradicts something else that was already established, vital information being left out, or a character acting way out of character for the benefit of the plot. In this case, this absolutely could count as a plot hole.
Audio problem: While a cool sound for the movie, the electric motor powering the M134 mini-gun vastly overpowers the sound of the actual gunshots from it, essentially making it sound like a turbine engine instead of machine gun. Plenty of videos available show this is impossible.
Continuity mistake: In the chopper, as Arnold asks about the backup, you can see Poncho sitting on the other side of Dillon. It's not until later in the scene where Poncho moves from his seat and sits next to Dillon for the remainder of the scene.
Other mistake: Right at the end, Arnold fires an arrow at the Predator which barely takes flight and fires very slowly. He is shown making the bow very tight so the arrow should come out very quickly.
Character mistake: When Mac describes what he saw after Blaine was killed, he states that he "capped off 200 rounds with the minigun." At the rate the minigun fires, and the length of time Mac was shooting, he fired at least 10 times that amount. Perhaps he meant to say "capped off 2000 rounds." This adds to another mistake: the ammo pack Blaine carried only holds 500 rounds but much more than that is fired during the course of the film.
Suggested correction: He actually says "capped off 20 rounds, in the minigun...full pack" just the word spacing is a bit odd. 20 rounds refers to his normal gun which ran out of ammo quickly.
No, he says "capped off 200 rounds." I've just watched it with subtitles on. What I heard (200) matched with the subs.
Continuity mistake: When Mac calls to Dillon about the scorpion you can see that there wasn't one on his back to begin with.
