Mattei claimed that he shot about 40% of the film, including all the early scenes in the film and the scenes in which the men are dressed in white anti-contamination suits. He elaborated that this included the entire beginning with the stolen suitcase, the helicopter scene, the scenes involving security guards storming a hotel room and the scenes where the zombies start to burn. Fragasso later said he directed a number of the additional scenes that Mattei is credited with having directed, but he let Mattei take full credit because he didn't want to get into a conflict later with Fulci. Both Fragasso and Mattei make cameos in the film as soldiers who are putting a corpse into an incinerator.