Morgan Creek Productions fired Paul Schrader after he had submitted a completed movie, saying that he had given them "footage without any of the bloody violence the backers had wanted". He had already made it clear in interviews that he was making more of a psychological drama than an all-out gore-fest. He was fired and Renny Harlin was hired to re-shoot the movie. Almost 90% of the movie was re-shot, re-casting several roles and adding and removing characters. Following the lackluster reception to Harlin's version, though, Schrader's version was finally released as Dominion: Prequel to the Exorcist (2005).
Both William Peter Blatty and Paul Schrader were nearly thrown out of this film's premiere for loudly laughing during the screening.
Nearly the entire cast (barring only Stellan Skarsgård) were either unavailable for the reshoots, or refusing to return out of loyalty to Paul Schrader.
Stellan Skarsgård is playing a younger version of Max von Sydow's character from The Exorcist (1973). Skarsgård is nearly a decade older than von Sydow was during the filming of the original movie.
When Morgan Creek hired Renny Harlin, he told them that Paul Schrader's version was complete crap and unsalvageable, and without any intention of actually signing onto the project, said that they'd be better off re-shooting from scratch. Much to his shock, James G. Robinson, the head of Morgan's Creek, agreed to this and offered Harlin an even bigger budget and paycheck than they had given Schrader. Harlin accepted the offer, and rewrote the screenplay alongside new writer Alexi Hawley.
Renny Harlin: [Finland] (at around 23 mins) small Finnish flag visible on top of a cabin next in Sarah's medical room.
Renny Harlin: [Finland] The character name of actor Roberto Davide is "Corporal Finn". The word "Finn" (pl. Finns) usually refers to a person from Finland.