When Danny climbs the pillar to retrieve the spear tip in the ventilation duct, he is crawling on his knees and then rises up while still on his knees. Once he retrieves and looks at the spear tip and is startled by the Predator's voice, he is shown to be losing his balance on his feet, trying to get his footing. At no point did Danny actually stand up...he cannot lose his footing because he was still on his knees.
When testing the alien spear tip, the female doctor says that they are viewing the image at 150,000 times normal magnification. However, when the camera cuts back to the doctor at the point at which she says "magnification", her lips aren't moving.
During the scene when the special forces team is getting slaughtered in the meat-house, Harrigan is suiting up and loads his M16/M203 weapon. He pulls the charging handle (to load the magazine), the scene then cuts to an indoor shot of the predator stalking the team. When the scene comes back to Harrigan, he pulls the charging handle to once again load the M16. There is no need to do this twice.
In the opening scenes, a banner on the screen identifies a news report as originating from "KCMQ Cable News". KCMQ is a broadcast designation, not a cable designation, which is not restricted to the three- or four-letter format beginning with "K" or "W". WTBS dropped its "W", leaving WGN as the only cable/satellite network to retain its regional designation.
When the Predator regains consciousness at the slaughter house resuming his chase after Harrigan, he sees Harrigan in infrared scope, a major bloop, as the Predator didn't put his mask back on. Anyone who watched the 1st installment must remember: without the mask the Predator can only see in red, with only minor distinctions (i.e. hand-to-hand combat with Schwarzenegger). The Predator didn't put his mask back on all throughout till the very end, occasionally using his respirator seen on the rooftop sequence etc. Inside the Predator's spaceship, again, he sees Harrigan down on the floor in infrared.
During the sequence where the special forces team is attempting to trap the alien, several shots were edited to go back and forth between the team and the ops center. When we first see the monitors, a little over two minutes has been recorded. When next we see one of the monitors, it show's only about one and a half minutes have elapsed.
When the Columbian is discovered hanging after the first shootout, the amount of blood on him changes dramatically from when first discovered to mere moments later when the Predator hoists him up further.
During the subway scene, Lambert draws his weapon to defuse the situation between the gang members and the other passengers. However, as the scene cuts back and forth between Lambert and the other individuals on the subway, the laser sight on his weapon switches between on and off.
When the Colombians are rearming themselves after getting back into their armory, one if them is shown placing a round on the bolt of the Iver Johnson AMAC-1500 rifle, then shortly later, it shows him pulling the bolt from the gun. These 2 scenes are obviously reversed, as the bolt has to be removed in order to place the round onto the bolt.
Before Scorpio is killed, he shoots his guns and nearly kills a cop in the hallway. When Scorpio runs to the top of the roof and we can see it from the predato'rs view, his guns are not showing any heat at all.
In the opening sequence, Harrigan chases one of the Columbian drug dealers up to the roof of a building. The Columbian fires numerous rounds before falling off the building, and shell casings are scattered over the roof. Harrigan climbs up and looks over the side of the building, and the shell casings are all gone. After looking over the roof, the shell casings are back.
During the opening credits, a radio voice is heard saying the temperature is 109°. As the camera moves in on the city, the buildings are shown dark and a few windows are red, indicating they're significantly hotter than 109. As it moves to the scene of the gun battle, human figures are also shown in red. But even when active, a human's core body temperature remains around 99°, and skin temperature is a few degrees lower. So with the air, ground, & buildings at 109, the humans should have appeared as dark silhouettes.
When Harrigan's crew first enter the penthouse and Lambert runs into the hanging body there is a crewmen in the shadows along the right side of the screen just visible under the body manipulating something with his hand.
The movie takes place in Los Angeles, but when the characters get on the subway, suddenly they are on San Francisco's BART system, not LA's Metro Transit Authority, which consists of light rail trains. You can see during a shot of the front of the train that it has a distinctive BA, the first two letters of BART standing for Bay Area, instead of the MTA printed on the side of the cars in other shots.
When Harrigan visits Danny's grave, he lays Danny's detective shield from the police dept on Danny's grave and walks away, kind of as a tribute. There is no way any police officer or detective would ever do that. To leave a genuine detective shield on a grave in public for anyone to come along and later steal, would give a civilian, or worse, a criminal civilian a real police badge to perhaps use to commit crimes with posing as a detective in the future.
The drug lord that falls from the roof of the building, after Harrigan shoots him, lands on a table. Considering his size and the length of the fall, the table would most definitely have been crushed or collapsed.
Voodoo is a distinctly American version of Hatian Voodou. A Jamaican drug gang might associate themselves with voodoo in order to inspire fear in rival gangs that don't know any better, but its unlikely they would actually practice voodoo to the extent shown in the film.
When Keyes is giving Lt. Harrigan a full explanation of just who and what the Predator is, he lists a series of places where the Predator has previously made an appearance; and among these places he cites Iwo Jima. Keyes explains that the Predator is "drawn by heat, and conflict". This elaborates on a similar insight shared in the first Predator film by the Mexican girl Anna who says that the creature only appears "in the hottest years". However, Iwo Jima is in the North Pacific, and its climate is not particularly hot. In February and March of 1945 when the famous battle was fought, temperatures ranged from the low 70's in the daytime, to the upper 50's at night.
DEA's agents control room appears to be equipped with an Ampex model 4100 vision switcher and an Ampex VPR-3 videotape recorder, these may be used for camera switching or video recording purposes, not for computer-programming.
The periodic table of elements is a sequential list, and it has no gaps for "unknown" elements. Every position from 1 (Hydrogen) to 118 (Oganesson) is known. The only elements that aren't on it are so heavy that they don't yet exist, and they'd be dangerously unstable & radioactive.
The "Chief Pathologist for the City" of Los Angeles remarks about the spear tip that Mike (Lt. Harrigan) brought to her that "none of these elements appear on the periodic table," and as such, she would have instantly recognized the spear tip as not from earth and would have pressed Mike incessantly to keep it, since the Lieutenant had no further use for it.
The Predator is shown walking with King Willie's decapitated head and King Willie is screaming. Decapitated heads cannot speak or make any other vocal noise since the lungs moving air over the vocal cords is required to vocalize. However, the scream is supposed to be from their earlier fight, and is merely overlaid for dramatic effect.
The human body needs to constantly radiate a certain amount of heat or it will overheat and the person would eventually die. Therefore, there is no such thing as an "infrared insulating suit", as it would be necessary to transmit this excess heat to the outside of the suit. This makes it impossible for humans to be invisible to the Predator's infrared vision.
Lt. Harrigan tells the scientist that he pried the "spear or harpoon tip" from Danny's hand. But Danny clearly drops the object (you can hear it impacting the ground) when the Predator encounters him near the A/C unit.
The Predator's telescoping pike is actually two special effects props, depicting a first and second stage elongation. In the scene where The Predator deploys the pike on the slaughterhouse rooftop, you can see him drop the first stage pike prop out of frame before the camera zooms in on him and he grabs the fully extended pike prop.
When King Willie is killed, there is a large splash (and subsequent smaller splashes indicating footsteps) when the predator jumps into the large puddle. However, in the first shot, there is no visible "shimmer effect" from the predator's invisibility cloak during the footstep splashes.
When the main predator's shipmates are fading into sight on the spaceship in one of the last scenes, the bottoms of their legs stop abruptly above the fog on the floor, showing it to be a green screen effect. Some predators who are already there have legs faded out at the bottom due to the fog.
When the alien ship is lifting off in the final scenes, the tunnel is filled with a fiery blast which Harrigan tries to outrun. The effect depicting the ships lights is off-center to the left of the actual blast. Just before the lighting effect disappears, it is roughly shifted to the left to try to match the blast.