The scene where Regan projectile vomits at Father Karras only required one take. The vomit was intended to hit him on the chest. Instead, the plastic tubing that sprayed the vomit accidentally misfired, hitting him in the face. The look of shock and disgust while wiping away the vomit is genuine. Actor Jason Miller, (Father Karras), admitted in an interview that he was very angered by this mistake.
The contortionist Linda R. Hager was hired to perform the famous "spider walk" scene, which was filmed on April 11, 1973. Ms. Hager was able to perform the scene by use of a harness and flying wires hung above the staircase used in the set; she would advise Friedkin when she was just barely touching the stairs with her hands and feet; and then she maintained that light touch as she was moved down the staircase by the harness and wires. William Friedkin deleted the scene before the film's December release. He felt it was "too much" of an effect because it appeared so early in the film. He later admitted that another reason for omitting the scene was that there was no way to hide the wires from view at the time. Almost 30 years later, Friedkin changed his mind and added the scene back for the extended 2000 version, with the wires digitally removed.
William O'Malley has told students that the movie is approximately 80% true. He claims the big discrepancies between the movie and reality were: it was a boy who was possessed, not a girl; the possession did not occur in Georgetown, DC, but outside the city in Maryland; and the color of the "pea-soup vomit" was not green. He claims most everything else in the movie did actually occur.
Actress Mercedes McCambridge, who provided the voice of the demon, insisted on swallowing raw eggs and chain smoking to alter her vocalizations. Furthermore, the actress who had problems with alcohol abuse in the past, wanted to drink whiskey as she knew alcohol would distort her voice even more, and create the crazed state of mind of the character. As she was giving up sobriety, she insisted that her priest be present to counsel her during the recording process. At William Friedkin's direction, McCambridge was also bound to a chair with pieces of a torn sheet at her neck, arms, wrists, legs and feet to get a more realistic sound of the demon struggling against its restraints. McCambridge later recalled the experience as one of horrific rage, while Friedkin admitted that her performance--as well as the extremes which the actress put herself through to gain authenticity--terrifies the director to this day.
In the documentary included on the 25th Anniversary Edition, the actors reveal that in many shots it was not necessary to "act", as what was captured on film were genuine reactions. For example, Ellen Burstyn mentions that her scream and facial reaction after being slapped by Regan were due to being pulled too hard by a harness. Linda Blair's screaming was a reaction to being bounced around on her bed. William O'Malley recalled that William Friedkin slapped him prior to shooting and this caused his hand to tremble while blessing Father Karras.
In an interview, Jason Miller stated that he had a major verbal confrontation with William Friedkin after the director fired a gun near his ear to get an authentic reaction from him. He told Friedkin that he is an actor, and that he didn't need a gun to act surprised or startled.
The bedroom set had to be refrigerated to capture the authentic icy breath of the actors in the exorcising scenes. Linda Blair, who was only in a flimsy nightgown, says to this day she cannot stand being cold.
In order to make Max von Sydow appear much older than his then age of 44, make-up maestro Dick Smith applied generous amounts of stipple to von Sydow's forehead, eyes and neck. His facial skin was then manually stretched as liquid latex was applied. When the latex dried, his taut skin was then released causing the film of rubber to corrugate. This daily make-up procedure lasted three hours and was apparently the cause of much anguish for von Sydow.
The studio wanted Marlon Brando for the role of Father Merrin. William Friedkin immediately vetoed this by stating that with Brando in the film it would become a Brando movie instead of the important film he wanted to make.
Linda Blair received her Best Supporting Actress Oscar nomination before it was widely known that previous Supporting Actress winner Mercedes McCambridge had actually provided the voice of the demon. By Academy rules once Blair was given the nomination it could not be withdrawn, but the controversy about Blair being given credit for another actress' work ruined her chances of winning the award.
One of the most famous scenes in the movie and the shot used for the posters and the cover of the DVD/VHS releases was inspired by the 1954 painting "Empire of Light" ("L'Empire des lumières") by René Magritte. It is the scene where Fr. Merrin steps out of a cab and stands in front of the MacNeil residence bathed in an eerie glow.
Director William Friedkin went to some extraordinary lengths to get realistic reactions from the cast. He fired off guns behind the actors to get the required startled effect. When Father Dyer is attempting to administer last rites to Father Karris, Friedkin was not satisfied after several takes. He took William O'Malley aside and asked, "Do you trust me?" O'Malley said yes just in time to get slapped across the face. Friedkin immediately said, "Action!" and the result is in the film. He even went so far as to put Linda Blair and Ellen Burstyn in harnesses and have crew members yank them violently.
In A Decade Under the Influence (2003), William Friedkin talks about the original poster that the studio created for the film. It was a drawing of Regan's hand holding the bloody crucifix that she masturbates with. The original tag line was "God help this girl". Friedkin rejected the poster, stating that the word "God" should not be used in a movie tag line.
Upon its 1973 release in the Middle East, the film was shown only in Lebanon while in the rest of the Middle East, the film was banned. On its re-release, the film got banned throughout the whole Middle East including Lebanon.
Mercedes McCambridge had to sue Warner Brothers for credit as the voice of the demon. William Friedkin, on the Diane Riehm Show (NPR, 29 April 2012) said that originally she didn't want a credit, saying that she wanted the audience to believe the voice was Regan's. However, after it was released she changed her mind, and was given the credit.
The substance that the possessed Regan (Linda Blair) hurls at Father Damien Karras (Jason Miller) is thick pea soup. Specifically, it's Andersen's brand pea soup. The crew tried Campbell's but didn't like the "effect."
When originally released in the UK a number of town councils imposed a complete ban on the showing of the film. This led to the bizarre spectacle of "Exorcist Bus Trips" where enterprising travel companies organised buses to take groups to the nearest town where the film was showing.
In the scene where the words "help me" arise out of Regan's torso, the effect was achieved by constructing a foam latex replica of actress Linda Blair's belly, writing the words out with a paint brush and cleaning fluid, then filming the words as they formed from the chemical reaction. Special effects artist Dick Smith then heated the forming blisters with a blow dryer, causing them to deflate. When the film was run backwards, it appeared as though the words were rising out of young Regan's skin in an attempt to summon intervention.
William Friedkin had to take an all-British crew to film in Iraq because the US had no diplomatic relations with Iraq at that time. They were allowed to film on conditions that included teaching Iraqi filmmakers advanced film techniques as well as how to make fake blood.
William Peter Blatty based his novel on a supposedly genuine exorcism from 1949, which was partially performed in both Cottage City, Maryland, and Bel-Nor, Missouri. Several area newspapers reported on a speech a minister gave to an amateur parapsychology society, in which he claimed to have exorcised a demon from a 13-year-old boy named Robbie, and that the ordeal lasted a little more than six weeks. Robbie was born June 1, 1935, resided at 3807 40th Avenue in Cottage City, MD, and was a member of St. James Parish. He entered the seventh grade at Bladensburg Junior High in the fall of 1947, and was removed in the middle of his eighth grade year on January 15, 1949. He had experiences that ended on April 19, 1949. He re-enrolled in the eighth grade at Bladensburg Junior High for the 1949-50 school year, then spent from the fall of 1950 until June 1954 at Gonzaga High School in Washington, DC.
Director William Friedkin eventually asked technical advisor Thomas Bermingham to exorcise the set. He refused, saying an exorcism might increase anxiety. Rev. Bermingham wound up visiting the set and gave a blessing and talk to reassure the cast and crew.
In the documentary "Fear of God", William Friedkin states that the studio execs would come up on a weekly basis to have a look at the shooting progress. They shook their heads continuously, believing that the movie was total ridiculousness.
During the session where Karras is recording his interactions with Regan, he asks the demon its name (in Latin) and the demon responds with what would could be considered a witticism on its part: "La plume de ma tante" (literally, "The pen of my aunt"). This is a attributed to elementary French language instruction and used in the early 20th century as an example of a grammatically correct phrase taught despite limited practical use. LIFE Magazine in 1958 described it as: "...the most idiotically useless phrase in a beginner's French textbook." In popular culture, the phrase can be used metaphorically to refer to something irrelevant. In this instance, it could be interpreted as the demon telling Karras in a roundabout way that its name is irrelevant - a common motif in stories of Godly agents fighting evil spirits.
There are tales about ominous events surrounding the year-long shoot, including the deaths of nine people associated with the production and stories about a mysterious fire that destroyed the set one weekend. Actors Jack MacGowran and Vasiliki Maliaros died before the film was released.
The refrigerated bedroom set was cooled with four air conditioners and temperatures would plunge below 30 degrees. It was so cold that perspiration would freeze on some of the cast and crew. On one occasion the air was saturated with moisture resulting in a thin layer of snow falling on the set before the crew arrived for filming.
Ellen Burstyn received a permanent spinal injury during filming. In the sequence where she is thrown away from her possessed daughter, a harness jerked her hard away from the bed. She fell on her coccyx and screamed in pain.
A filmgoer who saw the movie in 1974 during its original release fainted and broke his jaw on the seat in front of him. He then sued Warner Brothers and the filmmakers, claiming that the use of subliminal imagery in the film had caused him to pass out. The studio settled out of court for an undisclosed sum.
William Friedkin was supposed to attend a dinner the night he received William Peter Blatty's screenplay. Out of curiosity, he started reading the first few pages and ended up missing his dinner engagement completely.
There were originally many very brief "blink and you'll miss them" cutaway shots in the 1973 release film, intended to create unease in the viewer. For instance: when the priest is dreaming of his mother coming up out of the subway, there is a brief cutaway of a face (Eileen Dietz), painted black and white, grimacing. There are two other places where this image is displayed: when Regan, lying on the bed, turns to look at Father Merrin and Father Karras, and just after the head-turning scene. In the "The Version You've Never Seen", the same image is superimposed over other scenes in the film: the first can be seen on the hood of the stove when Chris MacNeil has just returned home from speaking with the doctors and the lights go out in the kitchen; the next image can be seen in the scene directly following the former, on the inside door of Regan's bedroom when Chris MacNeil goes to check on her after realizing that Sharon wasn't present in the house. The statue of "Pazuzu" (encountered by Father Merrin) can clearly been seen in the background during the exorcism in the original film. The face of the statue is also imposed onto Regan's bedroom door in "The Version You've Never Seen".
Although Mercedes McCambridge provided Pazuzu's lines from the moment when Karras confronts the possessed Regan for the first time up until the final confrontation, Linda Blair and Ron Faber also provided lines for Pazuzu. Blair's voice can be heard when the possessed Regan screams "Fuck me!" in a raspy, high-pitched voice. Faber provided two lines in this same scene, but he also recorded Pazuzu's lines during the entire "demonic head-spin" scene and he also provided a growl in the sequence where Karras is possessed by the demon.
In the disturbing scene where Regan is masturbating with the crucifix, Eileen Dietz was used for the shot where Regan belts her mother across the face. William Friedkin felt they needed someone with more heft physically to perform the stunt, and the double was shot from the back. The crucifix scene was filmed with Dietz, according to an interview with her in the documentary "Starz Inside: Fantastic Flesh: The Art of Make-Up Effects".
The actual residence in Georgetown that is used for the exterior shots has a rather large yard between it and the infamous steps. The window that leads to Regan's room is at least 40 feet from the top of the steps. This distance would make it impossible for anyone "thrown" from the window to actually land on the steps. In the movie, set decorators added a false wing to the house, so that Regan's supposed window would in fact be close to the infamous steps.
In one scene, the Jesuit president of Georgetown University (Thomas Bermingham) mentions that Father Merrin (Max von Sydow) is at "Woodstock". Audiences may think the reference is to the famous music festival that took place upstate New York in 1969. In fact, the Woodstock in the film is actually Woodstock College, a Jesuit seminary in Woodstock, Maryland. Opened in 1869, the seminary closed one year after "The Exorcist" was released. The Woodstock Theological Center, a nonprofit Catholic theological research institute on the Georgetown campus, succeeded the college and remains operational today.
On the documentary "Raising Hell: Filming The Exorcist (1973)" included with the 2010 Extended Director's Cut, author William Peter Blatty reminisces that the supernatural/demonic sequences did not inspire patrons to flee theater, nor were they responsible for nausea in the aisles. The scene in which Regan undergoes carotid angiography, using direct carotid puncture and pneumoencephalography was the moment in the Exorcist which upset theatergoers. This procedure entails cerebrospinal fluid being drained to a small amount from around the brain and replaced with air, oxygen, or helium to allow the structure of the brain to show up more clearly on an X-ray picture.
Lalo Schifrin's score was rejected (see also The Amityville Horror (1979)). William Friedkin later said that had he heard the music of Tangerine Dream (who scored his later film Sorcerer (1977)) earlier, he would have had them score this film (from the "Sorcerer" soundtrack liner notes). Friedkin actually hated the music so much that he yelled for the orchestra to stop playing, removed the reels that had been recording the music from the sound desk, and promptly threw the reels into the streets, all in front of Lalo and his wife.
Gonzalo Gavira was called on to create many of the special sound effects after William Friedkin recalled his work from El Topo (1970). One of the more memorable sounds, the 360-degree turning of Regan's head, was actually made by taking his old, cracked leather wallet and twisting it back and forth against the microphone.
Though often cited as one of the most shocking scenes in cinema, the crucifix masturbation scene was actually greatly toned down from that of the novel. In the source book, the scene is much longer, gorier and sexually explicit, with Regan suffering a broken nose, butchery of her genitals, and orgasming.
As advised by a studio executive, Director William Friedkin made several cuts to the movie prior to the release, citing that the scenes were unnecessary. This offended William Peter Blatty, the author of the novel and screenplay whom he had befriended, who thought these scenes formed the heart of the movie. Blatty even refused to speak to Friedkin for some time, but they eventually made amends. Many years later, when the immense popularity of the movie warranted a re-release, Friedkin agreed to re-evaluate some of the deleted scenes and put several of them back as a favor to Blatty, creating an extended "Version You've Never Seen". By his own admission, Friedkin tends to see this extended version as his favorite.
Several scenes were filmed that director William Friedkin would have loved to include in the movie, such as a scene showing Chris and Regan actually visiting some historic landmarks (as Chris suggests they should do in the movie). However, the soundtrack for the scene had gone missing. Another scene showed a possessed Regan slithering over the floor and upsetting several house guests by making obscene gestures with her tongue. The original negative of the scene got lost, and Friedkin refused to use a qualitatively inferior workprint he had of the scene instead.
Audrey Hepburn was William Friedkin's first choice to play the role of Chris MacNeil, and Warner Brothers supported him because of her good critical/commercial reputation with the studio, but she only agreed to do it if it was filmed in Rome. Jane Fonda and Shirley MacLaine were also approached. Anne Bancroft was another choice but she was in her first month of pregnancy and was dropped.
In order to bring some levity to the shoot, William Peter Blatty suggested shooting a scene (not for the movie, but to amuse everyone at the screening of the rushes) in which Father Merrin would enter the house, take off his hat, and reveal himself to be Groucho Marx, a friend of Blatty's. The parody would even go as far as featuring an appearance from the duck from You Bet Your Life (1950). Groucho was keen to do it, but William Friedkin got sick that day and the idea was abandoned.
For the vomiting sequences, Eileen Dietz doubled (uncredited) for Linda Blair, and later sued unsuccessfully for puking credit. Makeup veteran Dick Smith rigged Dietz's facial contours with sheets of heat-formed plexiglass that were secured at the corners of her mouth and behind her head. A camouflaged nozzle anchored in Dietz's oral cavity provided the apparatus through which the "vomit" could be forcefully discharged, fed by supply tubes discreetly embedded in the plexiglass on both sides of her face. Such was the complexity of the set-up that Dietz could barely swallow or close her mouth.
John Boorman had been offered the chance to direct, but declined because he felt the storyline was "cruel towards children". He did, however, accept the offer to direct the sequel, Exorcist II: The Heretic (1977).
Brazilian composer Eumir Deodato (famous for his 2001-Also Sprach Zarathustra heard in the movie Being There (1979)) lived in New York City by the time this movie opened, and was informed by friends that a piece of music he composed could be heard on the movie's soundtrack. He initially dismissed the warning, as he believed they were mistakenly identifying Tubular Bells (also part of the movie's soundtrack) as a composition of his own. Eventually, to clear this matter, his lawyer attended the movie with a concealed tape recorder. He recorded the whole movie, and played it back to Eumir over the phone, who finally recognized a composition of his own: "Carly and Carole", heard briefly at the party scene. Eumir's lawyer arranged a meeting with Warner Brother's legal team and asked for the movie to be pulled from circulation, eventually a compromise was arranged after a non-disclosed sum was paid.
Vasiliki Maliaros had never acted in a movie before. She was discovered by William Friedkin in a Greek restaurant. Her only acting experience was in Greek stage dramas. Friedkin selected her because she bore an uncanny resemblance to his own mother and William Peter Blatty felt she resembled his mother, too.
The scenes showing Father Karras in his room at Georgetown were filmed in Fordham University's freshman residence, Hughes Hall, fourth floor. Hughes was once the site of Fordham Preparatory school. Since there was no elevator at the time, the windows had to be removed in order to accommodate the camera on a crane. Each year, William O'Malley talks about his experience with the movie after students watch it on the same floor where it was filmed.
The Prospect Avenue apartment where the story takes place was once inhabited by the author, William Peter Blatty, while he was a student at Georgetown University. The house was owned by Ms. Florence Mahoney and is at the corner of 36th and Prospect. During shooting of the exterior scenes the crew had to build special sets to allow sunlight in to keep her garden plants from dying.
According to Panorama magazine, William Friedkin didn't give Brooke Shields the part of Regan McNeil because "she was too young for the part". It is known that Shields at the time wasn't known as an actress prior to the controversy of a similar film: Pretty Baby (1978).
William Peter Blatty based the character of Chris MacNeil on his good friend Shirley MacLaine. Prior to the 1973 production, MacLaine attempted to have a movie made of Blatty's novel and interested Lew Grade in backing the project, but the plans fell through.
Stanley Kubrick wanted to direct the film, but only if he could produce it himself. As the studio was worried that he would go over budget and over schedule, it eventually settled on Mark Rydell, but William Peter Blatty insisted on William Friedkin instead. After a standoff with the studio, which initially refused to budge over Rydell, Blatty eventually got his way.
The Greek song playing on the radio when Father Karras leaves his mother's house is called "Paramythaki mou" (My Tale) and is sung by Yannis Kalatzis. Lyric writer Lefteris Papadopoulos has admitted that a few years later when he was in financial difficulties he asked some compensation for the intellectual rights of the song.
Jane Fonda was offered the role of Chris MacNeil but declined it. This was during the Vietnam War, when she was notorious for her outspoken radical opinions, and it was rumored she had called the movie "a bunch of capitalist ripoff bulls***". However, in his book "William Peter Blatty on 'The Exorcist' ", the author reported that Fonda visited him personally to tell him the rumor was not true. She told him she had turned down the role because she didn't believe in fairy tales.
As recounted in Craig Hamrick's book "Barnabas and Company: The Cast of the TV Classic Dark Shadows (1966)", Denise Nickerson was considered for the role of Regan. Her mother took her out of the running after reading the "crucifix masturbation" scene in the script.
Although the song "Tubular Bells" is popularly referred to as the Exorcist theme, it is only played twice throughout the film. It is played briefly as Chris walks home and while Regan is being examined and filmed at the psychiatric hospital. It is only played again during the end credits.
Despite the studio's fears that the Motion Picture Association of America (MPAA) would give the film an X rating, it got an R, with no cuts whatsoever. The MPAA's decision, according to William Friedkin, was that it was "a brilliant, intelligent film" that deserved to be seen by a wider audience. Regardless, many American cities such as Washington, D.C. and Boston chose to disregard the decision and gave it an X.
Dana Plato claimed that she had been offered the role of Regan but her mother Kay had turned it down. In the book "Former Child Stars: The Story of America's Least Wanted" William Peter Blatty later said that he had "no such recollection" of this actually happening, and that Plato herself may have been the source for this rumor.
In 1981 the film was released on video by Warner Home Video, as one of its first UK releases. At the time there was no requirement that videos should be classified by the BBFC, so the video was simply released on the strength of its existing "X" certificate. Contrary to popular opinion, the video version was never included on the Director of Public Prosecution's list of "video nasties" and was never prosecuted for obscenity, testament perhaps to the popularity of the film and the high regard in which it was held. After the Video Recordings Act (VRA) was introduced in 1984 it became necessary for the film to obtain a certificate for video release from the BBFC. The video release was continually delayed on the recommendation of chief censor James Ferman, who advised Warner Brothers against submitting the film for a UK video certificate. A possible 1988 release was also vetoed by Ferman, who cited recent cases of child abuse as the reason. It was finally released on video fully uncut in June 1999, five months after Ferman's retirement as UK censor.
In 1981, the film was released on video by Warner Home Video, as one of their first UK releases. At the time, there was no requirement that videos should be classified by the BBFC so the video was simply released on the strength of its existing 'X' certificate. In 1988, after the Video Recording Act was introduced, the video was withdrawn from shelves when the BBFC refused to give it a video classification. It was not until 1999 that it finally received that classification and was re-released for home viewing.
William Friedkin traveled to England to meet with Bernard Herrmann about scoring the film. Herrmann insisted on doing the music in the UK and mailing the tracks to Friedkin. He was swiftly discounted after that. Lalo Schifrin was then appointed but he provided a full orchestral score which was the exact opposite of what William Friedkin had requested. (Friedkin wanted music that would inspire chills and a feeling of dread in the audience.)
In the arteriogram scene, the bearded man who assists the doctor is Paul Bateson. He was an x-ray technician at NYU Medical Center where that scene was shot and managed to get that small part. In 1979, he was convicted of the murder of a film critic and was sentenced to 20 years in prison. However, he bragged about and was a suspect in the murders of six men whom he said he picked up in gay bars, had sex with them and then murdered and dismembered their bodies and put them into plastic bags "for fun" in 1977 and 78. They were known as the "bag murders". Although investigators believed his story, he was never officially charged and those murders have technically never been solved. Bateson was released from prison in 2004.
In an interview on the January 12, 2007 broadcast of the Mr. KABC radio program it was revealed that actress/comedienne April Winchell was being seriously considered for the part of Regan MacNeil; however, she had developed a serious kidney infection which caused her to be hospitalized and ultimately taken out of consideration.
The ruins in the beginning of the movie are in Hatra, Iraq. These ruins have been preserved over the past 1400 years by various Islamic regimes. In 2014 the Islamic State of Iraq and the Levant (ISIS or ISIL) made threats to destroy this city stating that "graven images were not Islamic" and should not be allowed to exist. On March 7, 2015, Kurdish sources reported ISIS had begun the destruction of this ancient city.
During a 1984 reunion of the cast of The Exorcist on Good Morning America (1975), Ellen Burstyn told story of when she was in Tucson, Arizona filming Alice Doesn't Live Here Anymore (1974) and The Exorcist was opening in that city while she was there so she went to see it. She stated that the scene where Regan has her arteriogram was the part where most people fainted (this is the scene where Regan gets an arterial catheter inserted into her neck). After that scene she saw a woman wobbling up the isle so Ms. Burstyn followed her. When the woman finally fainted, Ms. Burstyn was at her aid, loosening her collar and talking to her. Then the woman began to come to and Ms. Burstyn realized that if this woman opened her eyes and saw her, this might cause the woman to panic. Ms. Burstyn's exact words were that she might think she was in the Twilight Zone or something. So, Ms. Burstyn asked assistance from another person to help the woman recover.
Popular belief and parodies give the false impression that Regan throws up on the priests during the exorcism, but she only throws up on Karras once when her first meets her alone. She does, however, vomit during the exorcism but slowly onto the bed and Merrin's stole.
William Friedkin originally intended to use Linda Blair's voice, electronically deepened and roughened, for the demon's dialogue. Although Friedkin felt this worked fine in some places, he felt scenes with the demon confronting the two priests lacked the dramatic power required.
The second medical test Regan has is a Pneumoencephalograph. A Pneumoencephalograph (sometimes referred to as an "air study") is a procedure in which the cerebral spinal fluid (CSF) is drained from around the brain by means of a lumbar puncture (puncturing the spinal column with a needle and removing CSF). The CSF is then replaced with oxygen or helium to allow the brain to show up more clearly on x-rays. This test was used in the 1970s to detect lesions in the brain. However, it was a very painful test with side effects such as severe headaches and vomiting due to the loss of CSF (which is replenished by the body in less than a day). The patient also had to be moved frequently while the x-rays were taken in order to displace the air which caused more discomfort to the patient. Furthermore, it relied on plain x-rays which do not clearly represent soft tissues such as the brain. While this test was used a lot before and during the early 1970s, it had limitations. The test did not show actual lesions unless they were on the edge of the structures that could be seen on the x-rays or large enough to displace tissue which could be seen on the x-rays. So, there could be a lesion there, but too small to be seen. Imaging contrast was not part of this test but used in a test that was often performed along with the Pneumoencephalograph called an Angiograph in which contrast was introduced into the vascular system and x-rayed. The Pneumoencephalograph was phased out in the late 1970s when more modern neuroimaging equipment became available.
The demon seen, but not named, throughout this movie is Pazuzu, a demon known in Assyrian and Babylonian mythology as the demon that brings famine during the dry seasons and locusts during the rainy seasons. He was the king of the demons of the wind.
The most disturbing scene to the majority of viewers was that of Regan having an arteriogram (the first test she had in the hospital). The director, William Friedkin, attributes this to the fact that the procedure itself looked very realistic, the man who played the doctor was an actual neurosurgeon in real life and that Linda Blair was as believable as a young, scared girl undergoing a scary, invasive procedure.
The trivia items below may give away important plot points.
The demon that possesses Regan MacNeil is named Pazuzu in the script, but this name is never mentioned in any cut of the film. During the film Pazuzu lies to Father Damien Karras claiming to be the Devil/Satan. Conversations with Father Lankester Merrin show this claim to be false.
The sound of the demon leaving Regan's body is actually the sound of pigs being herded for slaughter. This alludes to a story in the New Testament where Jesus cast out several demons, collectively called Legion, from a man and transfers them into the bodies of pigs. The pigs are then drowned, similar to Father Karris dying after accepting the demon.
The "Exorcist steps", 75 (or 74 - one is very small) stone steps at the end of M Street in Georgetown, were padded with 1/2"-thick rubber to film the death of Father Karras. The stuntman tumbled down the stairs twice. Georgetown University students charged people around $5 each to watch the stunt from the rooftops.
Besides Mercedes McCambridge's lawsuit for credit on the film, Eileen Deitz also charged that she played the role of the demon during the exorcism scene. Director William Friedkin denies this, and has cited that Deitz's actual screen time is less that one minute, as she served as little more than a body double for Linda Blair. Nevertheless, Deitz, as of 2014, continues to promote herself as "Captain Howdy," the demon from this film, in interviews and at horror conventions around the world.