Joss Whedon originally scripted the Newborn creature as a deadly four-legged, eyeless, bone-white creature with red veins running along the sides of its head. It had an inner jaw, similar to the all the other aliens. It also had a pair of pincers on the sides of his head. These pincers were used to hold its prey still as it drained the prey of blood with its inner jaw. The creature was also larger, nearly the size of the queen alien. In later script revisions, the creature was changed into a "more believable" hybrid of human and alien.
The first draft of the script contained an action sequence that took place in a garden contained within the spaceship "Auriga," with Ripley driving an electrically-powered jeep to avoid aliens attacking from all sides. This was to take place after the scene in the chapel but before the sequence where the Newborn is introduced. The sequence was cut due largely to budget constraints.
Nigel Phelps based the design of the spaceship "Betty" on a jackhammer. The "Auriga" was originally to be a vertical structure, but he abandoned this idea once he realized the difficulty of capturing the scope of such a ship design on film.
Sigourney Weaver made the behind-the-back half-court basketball shot successfully after two weeks of basketball practice, tutored by a basketball coach. Her conversion rate during that two weeks was about one shot in from every six. When the day came to shoot the scene, director Jean-Pierre Jeunet wanted to have the ball dropped in from above, rather than wait for Weaver to sink the shot herself, which "would probably take about 200 takes". Weaver insisted that the she could get the shot in herself, which she was finally allowed to do. She sunk the shot on the very first take, even though she was six feet further past the three-point line. Ron Perlman was completely stunned (and thoroughly impressed), and turned directly at the camera and broke character, saying, "Oh my God!" The editors looked at the shot and decided that there was "enough room to get the scissors in". Weaver was excited about making the shot, but Jeunet was concerned that audiences would believe the shot to be faked due to the ball leaving the frame. Upon Weaver's insistence, he kept the shot as it was. Weaver described the miracle shot as "one of the best moments in her life", after her wedding day and the birth of her daughter, of course.
In the scene where Dominique Pinon appears out of an elevator, his line originally was "Who were you expecting? The Easter Bunny?" However, Pinon kept saying "Eastern Bunny", to which his fellow actors would break out in laughter. The crew even started to print T-shirts with this line.
The actors were subjected to about 15 underwater training sessions in swimming pools around the Los Angeles area before arriving at the underwater set where they underwent a further 2 weeks of training before anything was shot. Sigourney Weaver missed most of this because she had been appearing in a play on Broadway just prior to filming.
Actor Ron Perlman nearly drowned while filming the underwater sequence. At one point, when trying to surface, he hit his head on a sprinkler in the ceiling, knocking him out cold. He was rescued by nearby film crew members.
Joss Whedon went through five different versions of the final battle with the "Newborn" creature, the first four versions of which all took place on Earth in such settings as a hospital maternity ward, a giant junkyard, a snowy forest and cliffside, and a desert.
The Auriga interactive computer is named "Father." In the original Alien, the computer's name was "Mother." There are even compatible scenes where people yell at Mother or Father for not responding to them.
Jean-Pierre Jeunet wanted to have a scene where a mosquito stings Ripley, then vanishes into smoke because of her acid blood. Eventually, he dropped the idea after the SFX team told him how much it would cost.
Winona Ryder agreed to do this film even before reading the script. She stated that she "didn't care if she died in the first scene", she'd do it. Ryder claimed that then she could boast about being in an "Alien" movie to her younger brothers.
When pre-production was underway, the original 'Alien Queen' could not be located and the molds that were used to build the original were damaged beyond usefulness. Fortunately, the original life-size puppet was located... in the personal collection of an avid Alien fan.
The studio wanted to cut the scene preceding Ripley's encounter with the alien queen that can be interpreted as a love scene, but decided to keep it only after Sigourney Weaver told them she would not promote the film if the scene was cut.
Ripley's outfit was going to be a different one than the dark red uniform she is wearing for the most of the film. After Sigourney Weaver saw Kim Flowers (Hillard) on the set, she wanted to wear the same costume. Hillard can be seen in the exact same outfit in the underwater scene.
Jean-Pierre Jeunet wanted to shoot additional action scenes using a fully digital Newborn creature. He wanted Ripley to be chased by the Newborn in the escape from the Betty scene, but could not realize it due to budget constraints. In the final film, a full-size Newborn creature can be seen in only one scene and almost all of the scenes involving the creature are animatronic.
The $50-60 million budget was significantly lower than the director and writers originally imagined. Therefore, sets were toned down in scale and a more claustrophobic shooting approach with a lot of close-ups to characters' faces was taken.
The part where the two aliens kill the third to get out of their cell, the intestines and guts and blood 'melting' through the floor was actually a platform descending with the intestines over top of it to give the impression of it melting through the floor.
For the luckless human victims which the renegades find, already having had the aliens burst out of their stomachs, the crew devised costumes which had stomach entrails stitched onto the outside. This was directly inspired by a T-shirt that was popular around the time of the release of Alien in which an alien fetus (and a lot of blood) was attached to the front.
Ron Perlman actually did his own stunt of hanging upside down off a ladder with his legs wrapped around the rung, firing two guns. The next day, when he came to take a shower, he discovered that he had severely lacerated the backs of his knees in doing so.
In her initial scenes with the Newborn, Sigourney Weaver makes a point of not looking in its eyes. This was a lesson learned from when she made Gorillas in the Mist in not making initial eye contact with a potentially dangerous animal.
In order to heighten contrasts, cinematographer Darius Khondji added silver to the printing process. This had the result of making the dark colors richer and giving everything else a metallic tinge. He also used an electric blue tint for the underwater sequence.
The underwater sequence marked the first time that Winona Ryder had gone underwater since a near-drowning incident that happened to her when she was 12 years old. The actress suffered a complete anxiety attack on the first day of filming in the underwater set.
One of the concept designs of the Newborn involved the creature sporting a likeness of Sigourney Weaver's face. This was abandoned as it bore too much of a similarity to Sil, the alien creature in Species.
The film's model miniatures were shot at a former Howard Hughes aircraft plant in Los Angeles. Visual effects supervisor Erik Henry and visual effects director of photography Rick Fichter used an advanced motion control camera system that required constant vigilance and re-alignment as the area was prone to small earthquakes and tremors.
Leland Orser's character is called Larry Purvis in the credits. In the original script, he was supposed to have his last name on his jumpsuit, and Christie calls him by that name. This scene was changed in the final cut, and the only person who ever refers to him as Purvis is Call, when they get ready to put him in the Betty's freezing chamber towards the end of the film.
The gaps between the four Alien films steadily decreased. There was seven years between the release of Alien and Aliens, six between Aliens and Alien³, and five between Alien³ and Alien: Resurrection. This pattern was broken in 2001.
Joss Whedon has commented on his dissatisfaction with the movie. Fans had speculated that the finished article deviated from his original script in some fatal manner, however he put such rumors to rest. His dialogue, action and plot were essentially intact. However he had written with a playful, tongue-in-cheek tone, which didn't work when the director decided to "play it straight". Eventually the Betty and her crew became the prototypes for Whedon's Firefly, which captured the tone he had aimed for in this movie.
Joss Whedon was unhappy with everything about the film. He later commented in 2005: "It wasn't a question of doing everything differently, although they changed the ending; it was mostly a matter of doing everything wrong. They said the lines but they said them all wrong. And they cast it wrong. And they designed it wrong. And they scored it wrong. They did everything wrong they could possibly do. That's actually a fascinating lesson in filmmaking. Because everything they did reflects back to the script or looks like something from it. And people assume that if I hated it then they'd changed the script...but it wasn't so much they changed it, they executed it in such a ghastly fashion they rendered it unwatchable.
Director Pierre Jeunet was given license to change the script as much as he wanted, and the final film is substantially different than Joss Whedon's original script. Characters and situations were merged, simplified or removed, and the overall tone was made more fanciful and less realistic. Things changed or removed include: An Asian assassin called St. Just (pronounced "San-Jhoost") was original part of the Betty's crew. Johner was described as being more of a crazy, psychopathic character. After the underwater sequence, the characters were then forced to climb up a 50 story lift-shaft, with aliens attacking them. After the Chapel scene, there was an action sequence in the ship's "farm", including a moment were the crew discovers the army has been growing cannabis. The Newborn alien was originally extremely deadly, the size of a Queen alien, and there was little emotional connection between it and Ripley. The final action sequence took place on Earth, ending with the surviving characters (including Ripley) deciding to stick together.
Paul W.S. Anderson was in talks to direct but was unable to take part due to scheduling conflicts. Anderson would still get his chance to direct an outer space opus the following year with Event Horizon. And of course he would visit the Alien franchise several years later with AVP: Alien vs. Predator.
The Newborns' skull was made of plaster so that it could be sucked out of the window into space. Cast only at 1/8-1/4" thick, it was scored into various pieces. Each piece was individually attached to a wire, so that when struck against the window and cracked, each fragment could be pulled out one by one.
On an episode of Conan, dated February 4th, 2013; William H. Macy revealed the last time he auditioned was for the role of Dr. Gediman. During the audition with director Jean-Pierre Jeunet, he felt the scene he was playing was so ridiculous, that he said "You know what guys, This is never going to happen." then got up and left the room.
The trivia items below may give away important plot points.
The first draft of the script included a different climactic fight between Ripley, Call, and the Newborn. Originally, after the Betty crash-landed on Earth, Ripley and Call were to battle the Newborn on a snowy mountain, using a "Harvester", a reaper-like farm machine which they had found during the garden chase sequence (which was also cut from the film due to budget limits).
The character of Dan Hedaya (General Perez) was initially going to die in a decompression scene, with him being sucked through a small hole in a window. However, Jean-Pierre Jeunet thought this was a much too spectacular death for such a minor character, so this idea was used for the death of the Newborn. Hedaya's eventual death scene (with him being bitten in the back of his head, and observing a piece of his own brain) was not approved by the studio, but was kept in the movie after the response of a test audience proved quite favorable.
The film ends with the Newborn being sucked out of a tiny hole in the spaceship's hull, an idea that was considered for the first film but abandoned because of budgetary constraints. It was also proposed for dispatching a minor character in one of the drafts of Alien³.
In the scene where Ripley discovers all of the other "failed" alien/hybrid clones of herself, she finds one still alive who begs Ripley to mercy-kill her, to which Ripley does so with a flame thrower. This idea was recycled from a deleted scene from Alien, where in the cut scene from that movie, Ripley finds Dallas and he asks her to mercy-kill him, which she does so with a flamethrower in a similar manner.