The scenes depicting the murder of the DeFeo family are fairly disturbing, and only gets worse when you realize that the murders actually happened.
George Lutz getting more erratic over the course of the movie, occasionally getting violent with friends and family. Near the end of the movie you start to fear that he'll kill somebody.
Demonic entity/"imaginary friend" Jodie's antics. First we have the babysitter trapped in a closet with no lock, who pounds on the door until her knuckles bleed. Then the light goes out and she's stuck inside for hours. When she's finally let out, the little girl she was babysitting explains Jodie wouldn't let her open the door.
When said girl complains to Kathy about being yelled at, Kathy tells her she should listen to George. Her response? "Jodie doesn't like George."
GET OUT.
Later, the same little girl is singing "Jesus Loves Me" as her mother walks down the hall. She comes in and we - but not her - see that the rocking chair in the corner of the room has been moving on its own as the daughter sings to Jodie. When the little girl complains her mother scared Jodie away and she went out the window, the mother goes to look in order to demonstrate Jodie is imaginary, only to be greeted by two glowing red eyes staring back at her. Keep in mind this is a second-story window with nothing outside to stand on. And then later in the movie, we get a brief glimpse of Jodie's form (as pictured above). That thing is huge.
The black pit to Hell in the basement filled with unknown black pitch.
The scary look on that lady's face when she said "it is the passage to Hell!" She sounded so evil!
More subjectively, the entire film's Kudzu Plot could be considered this IF it was meant to be intentional. The random, disconcerting moments and plot threads, often left without any real closure, give the film a sense understated creepiness in the vein of a David Lynch movie.
In his nonfiction book Danse Macabre,Stephen King recounts going to a matinee showing of Amityville composed mainly of older people, none of whom were reacting to the onscreen scares. When he asked several of the moviegoers, he learned that they were terrified of the financial horror, of the slow madness which comes with never being able to make ends meet, of having an expected windfall suddenly snatched away.
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