At one point, David Fincher was denied permission by the film's producers to shoot a crucial scene in the infirmary between Ripley and the Alien, where the latter menacingly closes in on Ripley. Against orders, Fincher grabbed Sigourney Weaver, a camera and shot the scene anyway. This scene not only appears in the final cut, but also featured prominently in trailers, and many regard it as the movie's most iconic shot.
The film's production process was so chaotic, and its reception by fans and critics so unfavorable, that it nearly ended David Fincher's career before he ever had a chance to gain momentum as a director. But two things ended up saving Fincher from permanent Movie Jail. The first thing was that Sigourney Weaver publicly (and often angrily) sided with Fincher against 20th Century Fox, telling journalists that the studio had made decisions that resulted in an impossible situation for the young director, and that he would have an excellent career if given further chances. The other thing was that producer Arnold Kopelson knew and didn't respect the management at Fox, and that was part of the process where he ultimately offered Fincher a new project a few years later; that project was Seven - Os Sete Crimes Capitais (1995), and its massive success re-ignited Fincher's career, making him one of the most respected directors of his time.
First-time director David Fincher disowned the film, stating in an interview with the Guardian: "I had to work on it for two years, got fired off it three times and I had to fight for every single thing. No one hated it more than me; to this day, no one hates it more than me". He cited constant studio interference during production, and actually walked out when the studio rejected his initial cut and ordered extensive re-shoots. He was not involved in the final cut, but his initial rough cut later became the basis for the 'Assembly Cut', a longer version of the movie released on DVD in 2003, and on Blu-ray in 2010. Although Fincher was asked to work on this Assembly Cut, he considered it but eventually decided against it, giving supervising producer Charles de Lauzirika his blessing as long as it was not called a 'Director's cut'. With regards to the new version itself, he stated that he has no comments on it, as he has never seen it.
While off set, Sigourney Weaver had to wear a wig as her then two-year-old daughter Charlotte didn't like to see her mother bald.
$7 million had been spent on sets that were never used thanks to the ever-changing script, before filming had even started. With a deadline looming and the studio getting anxious to get things back under their control, they would call writer Rex Pickett almost daily with constant demands for changes. It got to the point that whenever director David Fincher wanted to discuss Pickett's progress on the script, he would let the phone ring twice, hang up and call again, so that Pickett knew it was Fincher and not the studio harassing him. Even throughout filming, the script was constantly being re-written, with new versions faxed to the studio on a near-daily basis. Cast and crew often filmed a scene, and learned the next day that it had already been scrapped.