Sigourney Weaver made a point of not looking the Newborn in the eye whenever she had a scene with it. This was something she had learned from Gorillas in the Mist - to never look a potentially dangerous animal in the eye.
Ron Perlman previously had someone say "who were you expecting? Santa Claus?" at him in The City of Lost Children, by the same director as well.
Winona Ryder has said that she took the role in this before even reading the script, because she had always wanted to be in an Alien movie and could brag about it to her brothers. She joked that she'd still do it even if she was killed off in the first scene. She also jumped at the chance to appear alongside her idol Sigourney Weaver.
Sigourney Weaver was reluctant to do a fourth movie, after the rather final ending of the third. However when she read the script, the scene where Ripley sees the seven failed attempts at cloning her was enough to make her sign on. But she also gave other reasons:
The Danza: Carolyn Campbell as Carolyn Williamson.
Deleted Scene: Most of which are re-inserted on the Special Editionnote Jean Pierre Jeunet claims that the theatrical release is his preferred cut, and that the Special Edition is more of a gesture to the fans.
An alternate opening that appears to be from inside an alien's mouth - only to reveal is just a fly on the windscreen of the Auriga, which would then be squashed.
When the baby alien is removed from Ripley, she wakes up on the operating table and breaks the surgeon's arm. This foreshadows that she has part of the alien's DNA much earlier than in the theatrical release.
When Ripley is being shown various pictures - glove, fruit etc. - one of them is of a young girl who resembles Newt. Ripley would be visibly troubled by this.
As Ripley and Gediman are having lunch, Wren would tell her that Weyland-Yutani was bought out by Wall-Mart years ago.
A completely different sequence introducing the Betty crew. Elgyn flirts more with Hillard and tells Call and Vriess over the intercom to get ready. Cut to Call and Vriess working on some cargo, where Vriess would make a rude joke. This then goes to the scene of Christie receiving his weapons (which happens first in the theatrical cut), then back to Call and Vriess. Vriess throws a tool at Johner's head, he'd make a crack about Johner's alcoholism and he'd say something about deserving better company after he threatens Call.
More lines in the meeting between Perez and Elgyn.
After Call says they can freeze Purvis, she has another run-in with Johner. Christie then offers to keep an eye on Purvis just in case he starts acting funny.
Before diving underwater, Christie and DiStephano start geeking out about weapons. Christie also explains that their weapons are specially designed to operate in water, explaining why they're able to fight the aliens in the flooded kitchen.
A line averting the Inferred Holocaust of crashing the ship on Earth; Call says she recalibrated ground level - ensuring the ship will crash on an uninhabited quadrant. Ripley then tells Call about Newt.
A different ending taking place after the theatrical climax. Ripley and Call say the same lines except on Earth, showing the ruins of Paris behind them.
Dueling Movies: Alien Resurrection competed with Deep Rising. They came out from within a year of each other, and featured very similar plots.
Dyeing for Your Art: Winona Ryder, Ron Perlman, Leland Orser, Gary Dourdan, Kim Flowers, Dominique Pinon, Raymond Cruz and JE Freeman had to do fifteen training sessions in swimming pools in preparation for the underwater scenes. They had to do a further two weeks of training on set before anything was shot. Sigourney Weaver missed most of this, as she had Broadway commitments before filming.
Enforced Method Acting: Winona Ryder nearly drowned when she was a child, and the first scene they shot was the underwater through the canteen scene. Winona Rider had never been in water since her accident. The looks of anxiety before she goes in, and the utter terror on her face when they can't get out the other end? Yeah, those weren't faked. She had an anxiety attack on her first day of filming. The ironic thing? As a robot, Call shouldn't have looked nervous (after all, she doesn't need to breathe).
Executive Meddling: Note that, Joss's complaints to the contrary, the script to the fourth movie is substantially the same as the one he handed over (except for the ending, as he wanted the conclusion to be set on Earth but Fox instead pushed for the one still on the Auriga). It's the rest of the project that got screwed up. According to Whedon, he wrote the film as a camp parody and the studio chose to play it straight instead.
Fatal Method Acting: Ron Perlman nearly drowned during shooting as he hit his head filming in the aquatic escape. Winona Ryder also had an anxiety attack while filming the underwater scene.
Real Life Writes the Plot: The budget was significantly smaller than the previous Alien films, so the claustrophobic feeling was a result of toning down the sets and focusing on more close-ups.
Spiritual Successor: Firefly, as pointed out by Michael Marano in the essay River Tam and the Weaponized Women of the Whedonverse. That work and Resurrection share many character archetypes and plot elements (notably the "Weaponized Woman", in the form of Clone!Ripley and River Tam.) It's evident that Joss Whedon had his work on this film in the back of his mind while he was working on Firefly.
Throw It In: Sigourney Weaver actually made that behind-the-back-without-looking basketball shot for real (and in one take, no less), and the shock and surprise the other actors show is genuine. Ron Perlman notably looked directly into the camera and said "Oh my God!"; they cut the audio for the final movie.
Wag the Director: The studio wanted to cut the scene before Ripley's encounter with the queen, because of its sexual nature. Sigourney Weaver threatened to not promote the film if the scene was cut.
The climax would have actually taken place on Earth, and instead of the Newborn there was a massive white-colored Alien. Joss Whedon wrote five drafts, but Fox didn't want them so they wrote the eventual third act without his input. There is an alternate version of the ending where the crew land on Earth, and the final dialogue is exchanged near the ruins of Paris.
Jean Pierre Jeunet wanted to include a scene where a mosquito would bite Ripley - and then be dissolved from the acid in her blood. He had to drop the idea when the SFX team told him how much it would cost.
The Newborn had both male and female genitals during filming, but were digitally edited out at the orders of the studio.
Should Sigourney Weaver not come back as Ripley, the other idea for the film would be to have a clone of Newt as the protagonist instead.
The role of Call was written for Angelina Jolie but she turned it down.
Concept art of the Newborn showed it resembling Sigourney Weaver's face. This was abandoned, as the film Species used a similar idea.
Perez was supposed to die by being sucked through a hole in the side of his ship. Jeunet felt this was too spectacular for such a minor character, and so that death was given to the Newborn instead. Perez's actual death was almost cut, as the studio disliked it, but kept in after test audiences responded favourably to it.
Joss Whedon's original script had another member on the Betty crew - an Asian assassin called St. Just.