Lorraine Warren, played by Vera Farmiga in the The Conjuring movies, died a natural death aged 92 on April 18 2019. She had been a head consultant on all of The Conjuring projects, and an avid follower of the series.
The working title of the movie was plainly The Conjuring 3, but it was changed to The Conjuring: The Devil Made Me Do It as a direct reference to the infamous 1981 Arne Cheyenne Johnson trial.
(at around 3 mins) In the prologue of the movie when Ed and Lorraine are performing an exorcism, there is a shot of Father Gordon showing up and exiting from the cab which pays tribute to the horror masterpiece The Exorcist (1973).
This movie is about the story of Arne Cheyenne Johnson who killed his landlord in 1981. The story was described in the 1983 book "The Devil in Connecticut."
(at around 42 mins) When Father Kastner (John Noble) says that he prefers to keep his satanic objects locked up in his basement "like keeping guns off the streets", Ed and Lorraine exchange a meaningful look. In The Conjuring (2013), Ed said the exact same thing to a reporter while giving a tour through his basement full of cursed artifacts.