The first time Tom is hypnotized. The sequence starts out alright, only to abruptly smash to black when he falls asleep. Cue a blurry succession of disturbing images, the highlight of them being a young girl being strangled to death with some sort of plastic. To top it off, the whole sequence is accompanied by the distorted sounds of her screams.
Jake being abducted by Debbie. While her actions are understandable, the scene nonetheless manages to be prime worries for any parents watching the movie.
The second time Tom is hypnotized is a thousand times worse than the first. Midway through, Tom is attacked by Samantha, wrapped in the plastic she died in. The moment makes for a very effective Jump Scare.
Tom's general descent into madness throughout the film. Of particular note is when he starts digging holes in his backyard, and makes his young son (who has his own issues) help him, without any concern for his wellbeing.
The image of Samantha's corpse in the walls of the cellar. The fact that said image is accompanied by a staggered zoom and a scream doesn't help.
The flashback to Samantha's attempted rape and murder. The scene starts out disquieting, and is utterly horrifying by the end. Samantha starts to be taken advantage by Kurt and Adam, which causes Samantha to suffer a Freak Out (due to having the mental capacity of an eight-year old) and leads to her losing a tooth and her fingernail snapping. As she tries to fight the two off and freaking out more, Adam grabs a plastic-like tarp and smothers her with it. From her perspective. During this, you can hear Gob's cover of "Paint It Black" mixed in with Samantha's wheezing as she's suffocated.
Both Jake and Samantha: Imagine your child suffering from supernatural powers and unable to describe it all due to their age, all while for Samantha, imagine being a parent and your teenage daughter (who has the mental capacity of a little kid) never returning home.
