Not counting Amityville: The Awakening (2017), which is a completely original story, this is the only theatrically released Amityville film not to be based on a book but instead on the real life accounts of investigator Stephen Kaplan.
The frost that blows out of the basement onto Candy Clark was actually warm wax. She later admitted that she had to wash her hair with detergent to get it all out.
Like the previous installment, Amityville 3-D filmed the exterior scenes at the same house in Toms River, New Jersey and a house nearby for the exterior of Nancy's house. The interior was a set in a Mexico studio: Estudios Churubusco. The filmmakers almost never got the house to film at again. It was scheduled to be picked up and moved over one lot. They were only able to film the exterior shots before the house was moved. Originally the house had four quarter shaped moon windows, two on both sides. However, by the time of filming in 3D, the owners of the house did not want the eye windows on the side of the house facing the road so they modified them to look like small ordinary square windows. All shots of the "eye" windows (except for the most noticeable scene when John and Susan pull up to the house) had to be filmed on the side facing the river that has the sundeck.
Also known as Amityville III: The Demon.
The character of John Baxter is loosely based on Stephen Kaplan and his investigation of the house, who at the time was trying to prove the Lutzes' story was a hoax.