There were no sets built for the film. It was all shot on location at one large Italian villa. In fact the movie itself was written to be shot around that particular location.
Bruno:
Tennis balls?
Near the beginning of the movie the blade is seen cutting an adult magazine across the woman's right breast (from our point of view). Shortly afterwards when the composer examines the mysterious cuts in the magazine the slice marks appear across the left breast (from our point of view).
The 18-rated UK Vestron video release of this film in 1987 was cut by 1 minute and 50 seconds by the BBFC with edits to scenes of gore and heavy cuts to the bathroom murder. The 2001 Vipco DVD restores all the BBFC cuts and features the expanded Italian print. This runs around 12 minutes longer and includes extra (non-gore) scenes including night scenes of Bruno exploring the house and more red herrings & build-ups to murder scenes.
English, Italian