Claudio Fragasso envisioned the film as a tense psychological thriller with little to no gore. The original cut of the film resembled his vision. However, the producers were not happy with the lack of on-screen violence, and so Bruno Mattei, who had been hired as the film's editor, was tasked with shooting additional scenes to add more gore into the film.
Claudio Fragasso always intended for the film to be called "Night Killer". The producers renamed it for the Italian release, calling it "Non aprite quella porta 3" to make it an unofficial sequel to Tobe Hooper's La matanza de Texas (1974) which was released in Italy as "Non aprite quella porta" (Do Not Open That Door). Fragasso was not happy with the title change for the Italian release.
Director Claudio Fragasso was not fond of the gore scenes that Bruno Mattei shot and added into the film as it went against the kind of film he wanted to make which was less violent and more psychological.
Non Aprite Quella Porta 3 (1990) was released in Italy as an unofficial sequel to La matanza de Texas (1974), the exact same year that the official sequel La matanza de Texas III (1990) was released.
The additional violent scenes directed by Bruno Mattei caused a rift between him and Claudio Fragasso who felt betrayed by his longtime collaborator.