20th Century Fox wanted to sue Ciro Ippolito $10,000,000 for using Alien (1979) in the title. However, a British lawsuit pointed out that there was a novel from the 1930s called "Alien", so Ippolito won the case.
Although it was marketed as a sequel to Alien (1979), it's more of an in-name-only sequel with almost no connection to Ridley Scott's science-fiction classic.
Director Ciro Ippolito unsuccessfully tried to sue the producers of The Descent (2005) because of a slightly similar plot.
One of the first and few acting performances of Michele Soavi (credited as Michael Shaw) who later became a popular horror film director.
After Ciro Ippolito received the budget to make this film, he instantly spent a good portion of it on a new expensive car.
Ciro Ippolito originally wanted Mario Bava to direct the movie. He passed on, but helped a bit by giving some advice to the special effects team.
The Italian title card at the end ("... Ora Puo Colpire Anche Te") translates to "You could be next" or "You may be next".
After the release of the film, there briefly circulated the idea of making a sequel titled "Alien 3", it was to be directed by Bruno Mattei and with special effects created by Gaetano Paolocci and Francesco Paolocci. The producer was interested to see if there was an interest in the market, but after a careful analysis, he decided not to proceed with the making of the film. Although the project was never realized, there is an early poster design for the film.
After getting a cast, the direction was entrusted to Biagio Proietti, but after a week of various misunderstandings, he was ousted from the project. Ciro Ippolito therefore proposed the film to Mario Bava. However, Bava was already busy with another film and advised Ippolito to assume the role of director for Alien 2. Ippolito replaced Proietti a few days later, under the pseudonym "Sam Cromwell", which marked his directorial debut.
Mario Bava had suggested to Ciro Ippolito to use tripe as an economic system to realize the alien creature. Struggling with budget problems at the beginning of filming, Ippolito commissioned a toolmaker named Bombardone to buy tripe, then position it around the lens in order to create the illusion that the camera was the eye of the monster. To make the realistic effect, the meat was made to flicker like it were actually part of a living organism thanks to medical pumps. In doing so it created the "subjective" monster.
Given the great success of the film Alien (1979) by Ridley Scott, Ciro Ippolito decided to exploit the fame and realize a following apocryphal sequel. The idea of producing a sequel to the film came to Ippolito during a break from assembling one of his Neapolitan films, a genre that he did not care for anymore. Ippolito along with the editor Carlo Broglio saw a screening of Alien at the Adriano Cinema in Rome. After seeing the film, the two noticed a huge poster that advertised Zombie Flesh Eaters (1979) by Lucio Fulci, a successful unofficial sequel to Dawn of the Dead (1978) (released in Italy as Zombi). It gave Ippolito the inspiration to make this film.