Continuity mistake: As Harrigan is walking away from King Willie in the alley, Willie turns toward him to say, "Prepare yourself." His face is well-lit. In the next shot, Willie is facing away in the background and his head is entirely in shadow. He's turned and lit again for his next line. (00:47:00)
Continuity mistake: At the end of the fight in the slaughter house, Lt. Harrigan scrambles up a ladder and goes onto the roof with the predator in hot pursuit. A few moments later, Harrigan slams into the predator and they both fall off the roof. Suddenly, they are about 30 stories up dangling from a ledge. The slaughter house wasn't 30 stories tall...it wasn't even three stories! (01:16:05 - 01:24:25)
Continuity mistake: At the penthouse, the Predator lifts one of the Jamaicans on his wrist blades. Another Jamaican turns to see his friend dangling in the air with a claw sticking through his torso. In the next shot from the Predator's POV, the Jamaican is facing as before and still shooting at the wall like he didn't notice. After that, it shows the same man turning in an arc that should show the Predator, but it and the impaled man have disappeared entirely. (00:25:10)
Continuity mistake: When the Predator snatches the skull with the spinal cord attached from Bill Paxton's body in the subway tunnel, there should have at least been small amounts if not a good bit of blood left on the stairs leading up to the street surface by the time Danny Glover go to it while he was chasing him. (01:03:05)
Continuity mistake: On the end of the movie, when Harrigan is leaving the cave where the alien ship was, there is no way a ship that big could pass through such a small hole. (01:39:00)
Continuity mistake: In the slaughterhouse scene, Danny Glover's character pulls out a shotgun and blasts the Predator several times, knocking it flat on his back. Just as soon as you see the Predator hit the ground, you can see his mask start to fly off as though it's loosely attached. In the next scene, Danny Glover has to put some effort to pry it off, when it should have flown off in the first place. (01:18:45)
Continuity mistake: At the warehouse, when Harrigan and the other officers are looking at the carnage caused by the Predator, Danny points out the dead Columbian hanging from the skylight. The camera cuts to show the man hanging dead from the skylight, and you can see that he has a good amount of blood running down his body. When Harrigan is ordered downstairs, the scene cuts again to the body being hauled up by the Predator, except now the amount of blood has increased tenfold, looking almost like someone threw a bucket of blood on the corpse. (00:13:40)
Continuity mistake: In the beginning, after the gang retreats into the building, you see what appears to be the leader sniffing from a golden container. After a quick cut to the gang getting ready, you see his moustache covered with white powder. After another cut, a closeup shows his moustache is clean, way too quick to have cleaned up.
Continuity mistake: When the Columbians are in the armoury near the beginning, they all look up as a skylight shatters. In the slow motion shots, you can see the leader turn away from the glass. But, then it shows him in a closer shot, and he's still facing the falling glass, and falling back away from it, shielding his face with his hands.
Continuity mistake: At the start of the film, Glover's character blows away the Colombians with a shotgun outside their drug den. Immediately afterwards we're shown the Predators POV (in thermal vision) - looking directly down at their bodies, which show up a greenish color. This would indicate their body temperatures dropped to a much lower level impossibly fast. (00:07:00)