The movie follows a young woman named Sarah and her son, Chris, when they move to rural Ireland near a forest, where a large hole in the ground exists. After strange events, she starts suspecting that her son might have been switched by something else.
The Hole in the Ground contains examples of:
- Ambiguous Ending: Sarah manages to rescue Chris—the real Chris—from the titular hole in the ground, burns down the house with changeling Chris inside, and moves back to the city. However, when taking photos of Chris riding his bike outside, his face is very blurry compared to the rest of the photo, and the last shot is of the wall behind Sarah... which is covered in mirrors, suggesting that either she still isn't entirely sure whether she's rescued her actual son or she is sure but will be forever paranoid against losing him again.
- Beauty Is Never Tarnished: Averted. Sarah gets increasingly bloodied and muddied during the course of the film, and she's covering a nasty scar with her bangs.
- Bluff the Impostor: 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, only for them all to bounce flat, ultimately convincing her she's dealing with a changeling.
- Book Ends: Sarah and Chris start and end the film surrounded by mirrors.
- Cassandra Truth: Nobody believes James or Chris are changelings, further making their mothers questioning their own sanity.
- Changeling Tale: What the film ultimately is. Specifically, Chris was/is the changeling in question.
- Cloudcuckoolander: Noreen, the old lady who lives near Sarah and Chris, and who claims that Chris isn't Sarah's son.
- The Cloudcuckoolander Was Right: Chris turns out to be a changeling after his return from the forest.
- Contractual Genre Blindness: A very Irish Sarah spends most of the film ignoring all the changeling and fae folklore, along with local Haunted House Historian, just so the plot can happen. The moment she starts to take those things seriously, the whole gig is off within a single night.
- Creepy Child: Christopher after his return from the forest.
- Dark and Troubled Past: We never really learn what happened to Chris' father—if anything happened 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 restraining order or simply divorced.
- Daydream Surprise: While some Imagine Spots 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.
- Don't Go in the Woods: 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. And whatever lives inside of it.
- Doppelgänger: Changeling Chris, but more directly Sarah sees one of herself. One of the changelings hiding in the hole in the ground imitated her to confuse or replace her, just as she's exiting their lair.
- Driven to Madness: Noreen, the local Cloudcuckoolander, suffers from some unspecified condition after probably-not-accidentally killing her son thirty years ago. The actual reason is because she knows her son was replaced and she was unable to get him back.
- Evil Sounds Deep: During the singing number in school, Sarah starts hearing Chris in deeper and deeper voice, until it's heavily distorted. Like many such moments, it's her Imagine Spot rather than actual event, considering how the audience and rest of the class disappear halfway through.
- Eye Motifs:
- There are lots of closeups of eyes, or ocular objects in general. One standout example, if noticed by particularly observant viewers, is that Changeling Chris never blinks.
- The titular hole in the ground looks like an iris with an expanding and contracting pupil.
- Eye Scream: Changeling Chris claws at Sarah's eye whilst trying to get at the scar above it. Luckily, it turned out to be a hallucination, but it's still pretty horrific to see.
- Foreshadowing:
- There are enough 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.
- The first time we see Chris, it is when he is pulling faces in some bendy mirrors, which distorts his reflection. He is kidnapped by fae folk and replaced with a changeling, although we don't see the kidnapping itself.
- Haunted House Historian: Sarah's boss and friend, providing exposition on Noreen and the fate of her son James.
- Hiding Behind Your Bangs: 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 much insecure about the whole thing.
- Indy Ploy: The final twenty or so minutes Sarah has to come up with solution after solution while quite literally running for her life.
- Jump Scare: Used a grand total of two times. But since various scenes are built 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, mounting up tension with nothing.
- Kill and Replace: There is no goal or objective when handling captured children—they just starve to death, while the changeling takes over their life.
- Mama Bear: Invoked verbatim by Sarah when she comes to rescue real Chris.
- The Mirror Shows Your True Self: Noreen covered her house in these, and regularly checked her husband to see if he hadn't been "replaced." Extends to cameras and video as well, with Changeling Chris displaying what looks like a black, insectoid face in a broken rearview mirror.
- Nightmare Sequence: Sarah has a whole bunch of disturbing dreams, not even getting rest from her mounting paranoia when asleep.
- Offing the Offspring: Noreen killed her son due to her belief that he was a changeling. We see her real son's corpse at the end, proving she was right.
- Out-of-Character Alert: Christopher having lost his fear of spiders was one thing, but eating one?
- Primal Fear: Everything that happens underground, especially the very narrow and tight tunnel that seems to never end. Also, getting lost in a forest at night, anyone?
- Properly Paranoid: Noreen, despite being Driven to Madness, still installed mirrors all around her house, just to be sure her husband is still her husband.
- Psychological Horror: You think a Changeling Tale is scary? What about going insane and thinking your son isn't real while progressively becoming worse and more abusive parent? And Sarah is left paranoid for the rest of her life about the whole ordeal she went through.
- Riddle for the Ages: Quite a few. To keep them thematically together:
- What happened to Chris' father? Where is he? Is he even alive? Were he and Sarah even married? Did they divorce?
- Who killed Noreen? Was it Chris? Some other changeling? Suicide? Her husband?.
- 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? What's living down there? Was Chris dragged there or did he simply fall down?
- Sanity Slippage: Sarah starts to suffer from increasingly more paranoid dreams and daydreaming sequences as the story goes. And even when it's revealed Chris was indeed replaced with a changeling, there is no explanation for Sarah's mental breakdown prior.
- Scenery Porn: Only natural for a film set in rural Ireland.
- Shout-Out: The new wallpaper has a hexagonal pattern very similar to that of the carpet of the Overlook Hotel.
- Something Only They Would Say: Sarah confirms her fears when she offers Chris the "dust cheese", which he hates, and he happily spoons it onto his spaghetti, and follows it up with trying to play their game—which the replacement doesn't know.
- Super-Strength: Sarah has countless Imagine Spots in which Chris not only displays feats of inhuman strength, but is also malicious and harmful with it. While those are all going in her head, the Fake Chris indeed possess enough strength to throw an adult woman and drag her around with ease.
- The Unblinking: Changeling Chris never blinks.
- Would Hurt a Child: The fae folk who kidnap children and replace them with doppelgangers, with the implication that they drain their life essence.
