Corrected entry: Only six aliens were used for this film, painstaking editing made it look like there were hundreds of them. If you watch carefully, you'll notice there are never more than six aliens on screen at one time.
Corrected entry: During the briefing on the Sulaco Hudson's comment "Someone said alien. She thought they said illegal alien, signed up." was an inside joke. When Jeanette Goldstein was told they were casting a movie titled "Aliens" she thought it was about the U.S/Mexican border. So for her screen test she tried to look and sound as Hispanic as possible. So she was cast as Vasquez.
Corrected entry: When Ripley drives the APC into the station to pick up the marines, Hudson is apparently injured since Hicks has to practically carry him out of the alien hive and into the APC. But in subsequent scenes he has absolutely no trouble walking and his only injury seems to be the acid burn on his arm that he got after he made it to the APC. (01:17:10)
Corrected entry: In several of the wide shots you can see the screens on the motion trackers don't have their normal 'radar' type displays, they're just blank screens with a blinking light behind them. Two such instances are when Vasquez and Hudson are searching the colony for a life sign (which turns out to be hamsters in a cage) and right after the aliens cut power to the colony. (00:39:15 - 01:36:25)
Corrected entry: In the final showdown on the planet, the Aliens have burst in all around the Ops room. As Ripley is making her way to Medical, Gorman is in the upper corner of the screen, firing his handgun. Watch him, and you will see him point and shoot three times, you hear the clicks, but there is no noise, report or flash, just the actor pointing an empty weapon clicking away, as he apparently hits targets. (01:39:25)
Corrected entry: When the marines first arrive, the dropship lands for a few seconds, long enough for the APC to drive off, and no alien jumps on. When Hicks calls Ferro down again, we can see that the dropship is back in the transport's hanger. How did the alien get on board?
Corrected entry: When the marines look at the blueprint of the atmosphere processing plant, you can see that the plant is a smooth cone or dome like structure. You can also see the structure when the marines first arrive at the plant to look for the mising colonists. But when Ripley goes back to the plant to look for Newt, the structure of the plant changes completely to resemble something that looks like an off shore oil rig with spires and towers and pipes going all over the place.
Corrected entry: How is it that the marine drop-ship immediately plunges towards the planet's surface when released from the mother ship, but the mother ship itself appears to be in a stable orbit around the planet? One of the two ships is defying the laws of physics.
Corrected entry: In the hive, when Hicks puts his shotgun tip into an open egg, watch the camera angle of the camera mounted on his shoulder, the gun is off to the side and it should be in the middle of the screen seeing as how the camera is mounted on the shoulder holding the gun.
Corrected entry: When Ripley is in the atmosphere processor, trying to get away from the queen and gunning down drones, the camera keeps tracking the ammo counter, and it gets down to really low...about 9. She then shoots lots more rounds (if the previous speed that the counter goes down by is any comparison), far more than she had the ammo for.
Corrected entry: In the director's cut watch the temperature guages on the remote sentry controls, you only see the temperature change once, regardless of whether the guns were firing or not.
Corrected entry: In the director's cut, the marines had salvaged four robot autocannons with motion-targeting systems, two of which are placed in the access tunnel to the power plant. Right before they close the hatch, Hudson and Vasquez throw in a waste bin to test them; it is shot to pieces. Later, however, these autocannons still have their full ammo load, as seen on the computer counters.
Corrected entry: Towards the end of the movie, Ripley calls down both elevators to escape the Queen. When they arrive, she gets into the one on the right, leaving the Queen to use the one on the left. When the lifts reach the top, Ripley comes out of the one on the left and the Queen comes out of the one on the right.
Corrected entry: When we are shown the screen of the marines names there is a curious omission. It lists the marines by rank first: Lt. Gorman, Sgt. Apone, Cpl.Hicks, Cpl. Ferro, Vasquez, Drake, Spunkmeyer, Cpl. Dietrich, Frost, Wierzbowski, and Crowe followed by the non-marines Bishop, Ripley and Burke. Where is Hudson?
Corrected entry: In the scene where the baby alien pops out of the woman's chest, she eventually dies but her head leans to her side instead of hanging forwards as it should do but then in the next shot of her, her head is hanging forwards. (01:09:35)
Corrected entry: Lt. Gorman is supposedly knocked unconcious when an overhead storage compartment in the APC comes loose and dumps a whole hord of boxes on him. I guess he's a pretty fragile guy because if you watch the scene in slo-mo the only part of his body that actually comes in contact with the boxes is his right arm. His head is never hit or even touched by them.