Synopsis: Ripley wakes from hyper sleep in a penal colony to learn that an accident has claimed the lives of Newt and Hicks, and that something may have stowed away on her ship.
Early versions of the script and design featured a giant rustic monastery. Also, the alien itself would not be appearing.
The same "dipping bird" appears on the warden's desk as was seen in the original Alien (1979).
The creature that the alien impregnates was originally an ox, but was eventually changed because an ox was cumbersome and was seen as somewhat incongruous when placed in the film's environment. This sequence was later restored for the extended "Assembly Cut."
One possible idea for the film included a chest-burster coming out of Michael Biehn's character, Hicks. A replica of the actor with his chest torn open was created, but after Biehn discovered this, he threatened to sue the producers for using his likeness without his consent, and the idea was dropped. Later, the producers paid him to use his picture at the beginning of the film for the computer sequence. Apparently he received more money for use of this one image than for his role in Aliens.
Initially Renny Harlin was attached as director, but left to direct Die Hard 2. Then Vincent Ward came on board, but only lasted a few months before being fired after several disagreements with the producers. The scriptwriter, Walter Hill, was considered to direct the film as well, but he stepped back after David Fincher became available.
To create a convincing corpse of the character of Newt, the filmmakers created life size mannequins using the molds of Carrie Henn from Aliens.
Off-duty, Sigourney Weaver had to wear a wig as her then two-year-old daughter Charlotte didn't like to see her mother bald.
The alien in this movie differs from its predecessors in that the organic pipes on its back are now missing and it now has a more pronounced set of lips.
A cross is briefly seen on the planet surface to suggest the religion that some of the inmates have turned to. The model department held a competition to see who could design the best one. Four different models were created, and then David Fincher chose the version he liked best.
Because an early storyline of the movie involved aliens landing on Earth, an early trailer of the movie had the tagline "On Earth, everyone can hear you scream."