Some were filled with two kinds of chemicals that would mix while being riddled by bullets, and this mixture would then cause smoke that simulated acid burns. Tall, remote-controlled Alien puppets with very thin arms and legs were used in some shots, to make the creatures appear less like the traditional 'man in a suit'. Since this film called for many Aliens and the production would never be able to find so many tall people, 6-feet stunt performers were hired, reasoning that the humans and Aliens would hardly be seen in the same frame anyway. In Чужий (1979), a 7-feet tall performer had been used to portray the Alien, so that it would tower over the human characters.
