The real Perron family visited the set of the film.

When the movie was shown in the Philippines, some cinemas had to hire Catholic priests to bless the viewers before showing it. This was due to some viewers having reported a "Negative Presence" after watching the film. The priests also provided spiritual and psychological help to the viewers.

Eight generations of families lived and died in the house before the Perrons moved in. Andrea Perron suggested that some of the spirits from the families never left. Deaths included two documented suicides, a poisoning death, the rape and murder of an 11-year old girl, two drownings, and the passing of four men who froze to death. Most deaths occurred within the Arnold family, from which Bathsheba Sherman was descended.

The film was shot in chronological order.

The film was given an R rating by the MPAA. The filmmakers had thought the final cut had a chance of getting the more-box office friendly PG-13 rating, and asked the ratings board for clarification. The MPAA said simply that the film was so scary that there were no cuts or edits possible that would make it a viable PG-13 film; the filmmakers did not want to alter the film's tone and accepted the R rating without any appeals.

The film contains no sex or nudity, little profanity, tame and mostly bloodless violence, and brief depictions of alcohol and no smoking, yet it received an R rating. This was solely for its scare factor alone.

The state of Rhode Island does not require home sellers to disclose documented histories of a location's criminal activity (let alone alleged paranormal and supernatural hauntings) to potential buyers. This is why the Perrons were unaware of all previous events.

Director James Wan modeled the film's cinematography and atmosphere after vintage 1970s horror films.

The Warrens also investigated The Amityville Horror case.

Patrick Wilson and Vera Farmiga both traveled to Connecticut to meet with Lorraine Warren prior to filming.

The real Annabelle doll was actually a used Raggedy Ann doll that was bought by Donna's mother at a hobby shop and was known for not only leaving notes on parchment when there was no parchment around but also attacked a friend named Lou by mysteriously leaving claw marks on his chest. The makers of the movie decided to make a more sinister-looking doll of porcelain for the movie.

The production team also built a fifty-foot tall tree for the film.

The film broke box office records after bringing in a total of $41 million during its opening weekend. It stands as the third highest-grossing opening weekend for an R-rated horror film behind Paranormal Activity 3 (2011) and Hannibal (2001). The Conjuring made a total of $137 million at the domestic box office.

Ed Warren and Lorraine Warren investigated the Perrons' Rhode Island farmhouse in 1973 and 1974.

A movie based on the Perron family house had been in the works for over twenty years. It first surfaced when Ed Warren played a tape of his interview with Carolyn Perron to producer Tony DeRosa-Grund.

Director James Wan was working on the script one late night. He had just adopted a new puppy, who started staring at a supposedly empty side of the room and began to growl aggressively. Wan stated that his dog's head then followed something all across the room, but he did not see anything.

The production initially scouted a number of farmhouses to shoot in the Cape Fear region of South Eastern North Carolina, until they found the house featured in the movie. It is located on the Black River in Pender County. They only filmed the exterior of the home. All interior shots were filmed on set at Screen Gem Studios in Wilmington, North Carolina.

This film not only marked the second time composer Joseph Bishara has scored a James Wan-directed film, but it was the second time he had played a demon figure for Wan. He portrayed the demon embodiment of Bathsheba Sherman and previously played a lipstick-faced demon in Insidious (2010). Patrick Wilson stars in both Insidious and The Conjuring.

Andrea Perron wrote a three-part book based on her experiences in the house titled "House of Darkness, House of Light". Experiences written about in her book also appear in the film. Perron cites the film as a work of art and not a work of fiction.

In the original case Ed and Lorraine Warren were kicked out of the house as they were not able to help the Perrons.

This was the first film directed by James Wan to not feature a cameo of the Billy puppet doll from the Saw (2004) film series.

The Conjuring had the working title of "The Warren Files".

Lili Taylor researched The Exorcist (1973) to prepare for her role.

This film marked the third collaboration between James Wan and Patrick Wilson. The pair also worked together in Insidious (2010) and Insidious: Chapter 2 (2013)

Director James Wan wanted to take the feeling of the original The Haunting (1963) and apply it to The Conjuring.

In the scene where the Warrens showed students footage of an exorcism in the auditorium, the priest was played by George Zervos: chair of the Philosophy and Religion department at the University of North Carolina, Wilmington.

When the Hayes brothers and Lorraine Warren (a real-life demonologist) would chat on the phone about the script, they kept getting cut off by weird sounds and a lot of static. Then, out of nowhere, the line would suddenly go dead.

The mother of the Perron family claimed to have felt the same strange dark presence, similar to when she first experienced the occurrences depicted in the film. She later tripped and suffered some wounds, which put her in the hospital.

When the real-life Perrons visited the set location in North Carolina, they felt a cool wind whip throughout the set. They also noticed that the intense, sudden draft did not move or shake any trees.

The crew of the film built the set of the Perron's home nearly exactly like the real home.

This was the first film directed by James Wan that did not involve Leigh Whannell in any way.

Talky Tina from the Twilight Zone was one of the first devil doll characters in movies and television. (Talky Tina itself was a spoof on the real life doll Chatty Cathy; and the actress who supplied the voice for the Chatty Cathy doll; June Foray; also supplied the voice for Talky Tina). Talky Tina inspired Chucky from the Childs Play franchise; as well as the devil doll from the 1975 horror TV classic Trilogy of Terror with Karen Black; and Chucky and the devil doll inspired Anabelle from The Conjuring Franchise.

The Annabelle doll is used again in the film Annabelle (2014).

This was the nineteenth highest-grossing film of its year (2013).

This was the film debut of Kyla Deaver.

This is the first collaboration between actor Patrick Wilson and actress Vera Farmiga. They followed this with the sequel to this film, as well as the action thriller The Commuter (2018).

In the scene when the Warrens first meet the five daughters, the girls are watching an episode of The Brady Bunch. The scene features Maureen McCormick, Eve Plumb and Susan Olsen. Actress Shanley Caswell who plays eldest daughter Andrea starred alongside McCormick as stepdaughter/stepmother in a film previous to this one.

Stefania LaVie Owen auditioned for the role of Christine.

Lorraine Warren: Elder woman in the front row of the classroom when Carolyn is listening to the Warrens' presentation.

James Wan: [doll] The Annabelle doll.

At the end of the movie, Lorraine Warren gets off the phone and tells Ed Warren that the priest wants to discuss a case on Long Island. That case is the Amityville case, which was the basis for The Amityville Horror (1979).

The real Bathsheba Sherman was suspected of witchcraft and of killing an infant child, but her name was legally cleared after being found not guilty by a court of law. She died of natural causes in 1885, not by hanging as the movie portrays. She is buried in Harrisville, Rhode Island.

The real Lorraine Warren and Andrea Perron served as consultants to director James Wan and the screenwriters. They both claim the movie is accurate to the real story of what happened to the Perrons during the ten years they lived in the farmhouse.

If you listen closely to Lorraine's vision in the cellar as she tries to find any presences in the house, you can hear screams and a "No" said by Christine from her sleeping encounter, as well as a whispered "Look what she made me do," which is the voice of the servant spirit who Brad witnesses in the laundry room.