Mikael Håfström attended exorcisms to prepare for directing this movie. He was not allowed to witness them, but he could hear what was happening from outside the door.
The language Istvan Kovak (Rutger Hauer) speaks is Hungarian. It can be translated as: "My love, my flower, my bliss."
Shipped to theaters under the code name "Denial."
The hymn that Father Lucas sings near the end when Michael enters the room is "Jesu, Lover of my Soul," a Wesleyan Methodist hymn popular in Hopkins' native Wales. It is sung to the tune "Aberystwyth" written by fellow Welshman Joseph Parry. Both hymn and tune have interesting histories. Aberystwyth later developed into African liberation anthem "Nkosi sikelel i'Afrika" and part of the South African national anthem.
The first trailer for this movie featured music from Wojciech Kilar's score of Dracula (1992), which also featured Sir Anthony Hopkins.