In November 2005 Fox released an 'Unrated Edition' which runs nearly 8 minutes longer than the theatrical version. It features deleted plot and character scenes. It also has some alternative footage and added CGI blood effects. The story is better told. The violence and gore are stronger than in the PG-13 theatrical version.
The Theatrical version is the first of three existing versions of this film. Carrying the PG-13 rating in an effort to broaden the audience reach to kids and young teens, this version includes considerable creature violence, but only implied violence against human characters.
The "Unrated" home video version, released on DVD and Blu-Ray, contains numerous additional scenes, including an alternate opening set in 1904. As part of the "Unrated" feature, significant post-production changes were made to the film, most notably the addition of heavily edited CGI blood and gore. This change affected all human character deaths, as well as several creature deaths.
The Premium Cable version of the film (networks such as HBO) includes the addition of the 1904 alternate opening, but no additional scenes beyond that This version includes some, but not all, of the CGI blood and gore additions prevalent in the unrated home video release.
The original DVD had an additional deleted sequence: It shows a whaling station in 1904, and a whaler is being chased. He enters a building and tries to hide. As the camera cuts to the "Predator vision" though, it is clear that the hunter is chasing an Alien in the same room, which lunges at the camera. This sequence is approx. 1 min. 30 sec. in duration and now included in the 'Unrated Edition'.