The untold truth of The Exorcist

Few Hollywood films have caused as much controversy as The Exorcist. Its theatrical release in 1973 terrified and outraged audiences with a grotesque tale of demonic possession, and despite barely escaping an X rating, it made history by becoming the first horror film to earn a Best Picture Oscar nomination. It's still considered one of the scariest movies ever made, but the intrigue surrounding The Exorcist isn't limited to its shock value. In fact, some of the most compelling aspects of the movie come from behind the scenes. Here are some lesser-known facts about the classic that's been "turning heads" for over 40 years.

It was based on a real life exorcism

The film is based on William Peter Blatty's novel The Exorcist, which drew from accounts of an actual exorcism. Much of the source material for the book and the movie were culled from the journals of Jesuit priests who documented an exhausting battery of rituals they performed on a young boy named "Roland Doe" in 1949.

These priests claimed to have witnessed the following phenomenon: speaking in tongues, mysterious skin markings spelling the words "hell" and "evil," the violent shaking of the boy's mattress, and the breaking of hospital restraints and a priest's nose, to name a few. Many claims are admittedly embellished in Blatty's novel and the film adaptation (nowhere are hot green vomit and spinning heads seen in the diaries), and the gender of the child was changed to further protect the anonymity of "Roland Doe."

The Catholic Church supported the film

It may come as a surprise that many officials of Catholic Church praised the film upon its release. Not only did it drum up plenty of interest in Catholic tradition, it highlighted Catholic priests as heroes performing a time-honored ritual that dates back to the New Testament. The Church credits the film with a huge uptick in applications for the priesthood. The Catholic Church is known to be pretty protective of its secrets, but one official made an exception for The Exorcist. While doing DaVinci Code-style research for the film, director William Friedkin met with the president of Georgetown University (a Jesuit Institution), who reportedly handed him a red folder containing the diaries of the supervising priest in attendance, as well as eyewitness accounts of the 1949 exorcism.

Many believe its production was cursed

The production of The Exorcist was riddled with complications and tragedy. Early in production, the set depicting the home of the MacNeill family mysteriously caught fire, delaying filming. Even more mysterious: the set for Reagan's room, in which exorcisms would be filmed, remained completely undamaged.

Linda Blair's grandmother, Max Von Sydow's brother and two of the film's actors died suddenly during the course of production, and Jason Miller's son was nearly killed in a freak motorcycle accident. As many as nine total cast and crew members are rumored to have died during filming. Further, Ellen Burstyn sustained a spinal injury while filming a violent possession scene, which reportedly still bothers her today. As the unexpected problems piled up, the production extended well past its projected deadline. Friedkin even had the set blessed by a priest acting as a technical advisor for the film, though he refused to conduct an exorcism.

The film caused pandemonium upon release

You'd think one would have to be pretty mad to send death threats to a teenage girl. But that's exactly what some religious folks did to Linda Blair. Following the proclamation by renowned evangelist Billy Graham that "the Devil is in every frame of the film," hate mail poured in accusing Blair of "glorifying Satan." Warner Bros. had to hire bodyguards to protect her for six months after the film was released.

Several bizarre incidents surrounding the theatrical release of the film were reported. A man fell and broke his jaw during a screening, claiming the film's subliminal effects caused him to faint. He sued the studio and they settled out of court. This was just one of countless reports of paramedics being called to theaters to treat terrified moviegoers for hysterics and fainting. Some theaters even equipped seats with complimentary "barf bags."

Its antagonist is never named

The demon that possesses Reagan is called Pazuzu, but that name is never mentioned in the original book or film. Pazuzu is based on a mythological Babylonian figure, a king of demon winds, comprised of human and animal parts. Father Merrin finds an artifact in the desert at the beginning of the film that is supposed to be a portion of a Pazuzu statue. While the demon is seen, it wouldn't be named outright until the 1977 sequel The Exorcist II: The Heretic.

It features some pretty low-budget effects

Friedkin relied heavily on practical effects to create certain visuals, as well as drawing desired performances from the actors. He reportedly fired a gun before takes to produce maximum terror in his cast. Many scenes were shot in sub-zero temperatures to maximize the effect of actors' breath (and discomfort) on film. That vomit? Thick split pea soup. The sound of Reagan projectile vomiting was produced by a recording artist who regurgitated mushy apple and raw egg. In another creative "twist," the sound of Reagan's head turning was created by a crew member who twisted his leather wallet into a boom microphone. The screams of the demon being cast out of Reagan are actually recordings of pigs being driven to slaughter.

According to the filmmaker, it isn't a horror movie

According to Friedkin, all these years of terror might have been a case of mistaken intention. As he's put it, rather than a horror movie, he felt he was making a story about the "mystery of faith." As he put it, "I didn't set out to make a horror film, but by now, I have accepted that it is." That's a noble point of view, but the much-maligned Exorcist sequels and prequels have kept the franchise pretty squarely in genre film territory.