Originally, Soavi and Argento wanted to shoot the movie in the Lorenzkirche of Nuremberg (Germany), and even did some test shots there. However, it was abandoned because the town of Nuremberg didn't wanted a horror movie to be shot there.
When Father Gus, as a recreational archer, is using a bow to shoot at a target, he is not wearing a wrist guard. This is a painful mistake even a beginner would only make once.