Notes

* AdultFear:
** Your child is growing up and you can't recognise it anymore or communicate with it as you did previously.
** You are starting to suffer from SanitySlippage and this in turn starts to affect your parenting skills and ability to take care for your child.
* BluffTheImpostor: Eventually Sarah starts to do it ''on a regular basis'', constantly throwing at Chris various details and elements of his normal behaviour, favourite tastes and activities, [[spoiler: only for them all to bounce flat, ultimately convincing her she's dealing with a changeling]].
* CassandraTruth: [[spoiler: Nobody believes James or Chris are changelings, further making their mothers questioning their own sanity]].
* ContractualGenreBlindness: A very Irish Sarah spends most of the film [[spoiler: ignoring all the changeling and fae folklore]], along with local HauntedHouseHistorian, just so the plot can happen. The moment she starts to take those things serious, the whole gig is off within a single night.
* DarkAndTroubledPast: We never really learn what happend to Chris' father - if anything happend at all - and how Sarah gained that badly healed scar on her head, to the point her doctor starts to question if it really was an accident, or maybe some other way. We don't even know if the boy's father is alive, with restrain order or simply divorced.
* DaydreamSurprise: While some {{Imagine Spot}}s of Sarah are clearly her fantasies, breaking rules of physics or making people disappear into thin air, others are ''not'' and she herself can't tell or ever be sure if they are real or just going in her head.
* DontGoInTheWoods: The forest is plenty scary by itself, with nothing else added to the equation, and it's very easy for a boy like Chris to simply get lost in it. Then there is the titular hole. [[spoiler: And whatever lives inside of it]].
* DrivenToMadness: Noreen, the local Cloudcuckoolander, suffers from some unspecified condition after - probably not - accidently killing her son thirty years ago. [[spoiler: The actual reason is because she knows her son was [[KillAndReplace replaced]] and she was unable to get him back]].
* EvilSoundsDeep: During the singing number in school, Sarah starts hearing Chris in deeper and deeper voice, until it's heavily disorted. Like many such moments, it's [[spoiler: her ImagineSpot rather than actual event, considering how the audience and rest of the class disappear halfway through]].
* {{Foreshadowing}}: There is enough of {{ChekhovsGun guns}} and hints spread in the first act to cobble together not only what's going on, but also what's going to happen. Doesn't make the film any less engaging.
* KillAndReplace: [[spoiler: There is no goal or objective when handling captured children - they just starve to death underground, while the changeling takes over their life]].
* IndyPloy: The final twenty or so minutes Sarah has to come up with a solution after solution while quite literally running for her life.
* JumpScare: Used grand total of three times. But since various scenes are build intentionally around the expected and telegraphed jump scare, only to never have one, this leads to a tricky situation to decide ''which'' moment will be a "real" jump scare, [[NothingIsScarier mounting up tension with]] ''[[NothingIsScarier nothing]]''.
* MamaBear: Invoked verbatim by Sarah when she [[spoiler: comes for rescue real Chris]].
* NightmareSequence: Sarah has a whole bunch of disturbing dreams, not getting rest from her mounting paranoia even when asleep.
* PeekABangs: Thanks to an accident, Sarah's forehead has a nasty, non-stop irritated scar. She has it perpetually hidden with her bangs and is very self-conscious about it.
* ProperlyParanoid: [[spoiler: Noreen, despite being DrivenToMadness, still installed mirrors all around her house, just to be sure her husband is still her husband]].
* PsychologicalHorror: You think ChangelingStory is scary? What about ''going insane and thinking your son isn't real'' while progressively becoming worse and more abusive parent? [[spoiler: And Sarah is left paranoid for the rest of her life, precisely because the ChangelingStory is proven real]].
* PrimalFear: Everything that happens [[spoiler: underground, especially the very narrow and tight tunnel that seems to never end]]. Also, getting lost in a forest at night, anyone?
* RiddleForTheAges: Quite a few. To keep them thematically together:
** What happend to Chris father? Wher is he? Is he even alive? Was he and Sarah even married? Did they divorce?
** [[spoiler: Who and ''if'' killed Noreen? Was it Chris? Was it some other changeling? Was it a suicide? Did her husband did that?]].
** Do people even know about the massive sinkhole in the forest? Does the sinkhole exist as it is shown, or is just Sarah's projection? [[spoiler: What's living down there? Was Chris dragged there or simply fell down?]]
* SanitySlippage: Sarah starts to suffer from increasingly more paranoid dreams and daydreaming sequences as the story unfolds. [[spoiler: And even when it's revealed Chris was indeed replaced with a changeling, there is no explaination for Sarah's mental breakdown prior]].
* SuperStrength: Sarah has countless {{Imagine Spot}}s in which Chris displays not only feats of inhuman strength, but also being malicious and harmful with it. [[spoiler: While those are all going in her head, the Fake!Chris indeed possess enough strength to throw an adult woman around like a rag doll and drag her around with ease]].
* UncannyValley: There is something very, very wrong with Chris, but Sarah can't even name it properly. The boy is alright and behaves ''almost'' like always, but there are those countless, tiny deviations that make her question if the boy is even her real son.