Emmanuele Mazziotti, Andrea Mazziotti, Erika Vaterlini and Matteo Vaterlini are cousins of Davide Melini, in real life.
The closeup shots of the killer's hands, as well as the opening narration, were performed by director Davide Melini.
The special effects were made by Rosario Prestopino and Diego Prestopino, father and son in real life.