Audio problem: After Dutch has fired the rocket at the Predator standing on the log, the Predator shoots several times. Then you can hear it shoot one more time, but you can't see any blast coming from it. (01:24:35)
Visible crew/equipment: During the final battle, shortly after Dutch runs by a plant that moves and catches the Predator's eye, watch as the Predator takes a few strides from rock to rock. When he jumps down off the last rock you can see a cable above his head helping him make his jump. This same cable can also be seen from a different shot about ten seconds later when Dutch runs into the Predator. (01:29:45)
Continuity mistake: When Dutch is running from the Predator after he sets the grenade off in the tunnel sequence, he avoids the Predator's gun blast by leaping and swinging on the branch of a dead tree. As Dutch's flying through the air, you can clearly see that it is a real branch. But as the screen switches to an explosion and back to Dutch, the branch is now some prop 2x4 and collapses as Dutch now plunges into the pond below. (01:33:20)
Revealing mistake: Watch when the Predator reaches over to activate his self-destruct mechanism. The wristblades clip right through the glowing special effect on his blood. (01:40:05)
Revealing mistake: When the Predator self-destructs and the people in the chopper look out at the blast, the "painting" of the explosion is still and does not move or change like a normal explosion would. (01:41:05)
Continuity mistake: When Mac first shoots up the jungle, he runs out of ammo. From the behind shot the barrel of the mini gun isn't spinning. Then, from the front shot when Mac releases it the barrel is spinning. (01:46:25 - 02:46:30)
Revealing mistake: As the Predator tends to his wounded leg, one of his claws can be seen bending as if made of rubber.
Revealing mistake: Mac and Dillon go after the Predator. The Predator is sitting in a tree, and Mac points him out to Dillon. They both agree that they see it and take position. Mac crawls underneath the alien and is killed by his laser. The Predator then sees Dillon and lasers his arm off. Dillon's arm falls to the ground with the gun firing. Quickly Dillon turns and reaches for the machine gun around his neck. When he turns you clearly see his bloody right stump and his right arm sticking out the bottom of his jacket. [Note: As far as I can work out, this has been cunningly edited out of the UK DVD version].
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: 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.
Continuity mistake: In the scene at the end when Arnie crawls into the booby trapped gully you can see the Predator behind him with the knives on his right arm already extended. The camera then switches to a shot of the Predator extending the knives to finish Arnie off.
Continuity mistake: Near the end of the film, Arnold is lying in wait for the Predator after he lights the bonfire. It is pitch-black, except for the moonlight and the fire. But in the shot when the Predator jumps down through the trees, the skyline is brighter - almost early evening in brightness.
Visible crew/equipment: When the predator has been hit by Arnie, the camera and cable is reflected on his face. This also happens when Arnie is calling for Billy - you can see it reflected on his arm.
Continuity mistake: In the scene where the female prisoner falls to the ground and pretends to be hurt, then throws leaves in the soldier's face and tries to escape. She is stopped by another soldier, standing in her path with a gun in her face. The sequence with the gun pointed at her head is filmed in two shots. One looking up at the soldier holding the gun, the other with the gun hovering in her face. Every time it changes between these two camera angles, we find the soldier's hands in two completely different positions on the gun he is holding.
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.
Suggested correction: It's not clear how much powder came out because it's too dark to see. It could be assumed that it was a lot but it could equally have been not much that took some time, and turning of the shell, to come out. That said, a standard low-velocity, launcher-fired 40 mm grenades generally have explosive loads of 30-50 grams.
Revealing mistake: In several scenes, you can see the BFAs (blank firing adapter) in the team's M16s, proving they've been rigged to fire blanks.
Continuity mistake: During the big firefight after Blaine was killed, Dutch moves his hand forward to eject the magazine from his weapon. An instant later, the side view shows his hand on the handgrip and the magazine being ejected - way too quick to get his hand back on the grip.
Revealing mistake: When Bill Duke picks the scorpion off Carl Weathers' shoulder with a knife, you can blatantly see some gum or similar that's been used to stick the scorpion onto the tip of the knife. Even if it's meant to be Bill Duke's gum, it's not on the tip of the knife before he stabs it.
Suggested correction: It isn't gum, it's literally the scorpion's guts.
There are no guts in the scorpion's body, so it's obviously some material to stick scorpion to the tip of the knife, and it's blatantly visible in the close shot.
It's the abdominal fluid. It probably is gum in real life but if you kill an insect you will find it has a gum-like fluid in its abdomen.
Visible crew/equipment: Dillon again, after having his (visible) arm shot off the Predator moves in and picks him up off the floor, at the bottom of the screen you can see the plank that is used to elevate him. (Only visible on the full-frame video).
Revealing mistake: When Arnold is heading into the trees after building his bow and arrows you can see a silver eye bolt on the top of the bow where the string would attach.
