WARNING: Per wiki policy, spoilers are off on Nightmare Fuel pages. All spoilers are unmarked.
- At the start of the film, Adelaide is wandering around a house of mirrors. She rounds a corner... and sees the back of her head in the mirror in front of her. It takes your brain just long enough to realize, "Wait, mirrors don't work like that!"
- It's bad enough being pursued by a crazed group of killers, but a crazed group of killers that looks exactly like you and your children?
- And as Adelaide points out later on into the trailer, not only do they look like you but think just like you, which means they know your every move and thought before you even can conjure it.
- Another brief trailer shows that Adelaide is not exaggerating. It shows Adelaide trying to sneak up and attack Red, her doppelgänger, who is sitting down, only for her to almost casually dodge the strike aimed at her head and pull out her golden shear scissors, ready for a fight.
- Hell, even the very beginning of the movie isn't alone! It straight-up opens with thirty seconds of very creepy text slowly fading into view on a black background with an ominous ambient noise in the background, each line lingering before fading away. This opening alone serves as pure Paranoia Fuel even long after the movie ends, especially not after you learn that this harrowing real-life fact subtly ties into the true nature of the family's doppelgangers...
- Jason's doppelganger is seen standing close to a fire, but it doesn't seem to be affected, and (depending if this is an editing trick) we can see him basically absorb the fire into him. Unless you reverse the clip in question and realize he could be deliberately walking backwards into the flames... which, of course, the actual film revealed to be the case.
- Red’s utterly unnerving “Be careful”, followed by a seriously creepy chuckle.
- Even the way the Tethered move is terrifying. From Pluto's doglike scampering to Red's unnaturally smooth and flowing movements, everything about them just seems wrong.
- The current poster for the movie depicts Red (Adelaide's Tethered counterpart) weeping in fright while removing a creepily realistic mask of Adelaide's face from her own face.
- This takes on a more frightening meaning following The Reveal — that Red, the original Adelaide, was forced to grow up among the Tethered.
- Looking at the left eye-hole of the mask, where Adelaide's other eye is half covered, it almost looks like the mask is looking at you from the corner of its eye.
- Red’s “fairy tale” that is delivered in her stifled and raspy speech, which describes the horrible upbringing she had. Creepy as she may be, she's not unworthy of sympathy here.
- The Tyler family Tethered show exactly how horrifyingly efficient they are when they aren’t playing with their food, flawlessly infiltrating the house and killing the entire family in seconds.
- As Kitty bleeds out, she tells her virtual assistant Ophelia to call the police. Instead, Ophelia royally fucks up by playing "Fuck tha Police!" by N.W.A., which allows her Tethered counterpart to finish her off.
- Tex, Josh's Tethered, survives a fire poker to the brain.
- The scene of Tex managing to briefly and silently bait Adelaide to come inside by disguising himself as Josh. Although he can't speak, it's so nearly convincing yet...off.
- The state of Tethered existence; so long as their counterparts live, they're forced to dance to the actions of their counterparts. It's made explicit by Red that their ruthless actions and madness is due to having never truly had free will and desperately wanting to escape the influence of the Psychic Link.
- The Not Quite Dead Tyler twin who attacks Adelaide, her face caked in blood as she crawls and screams as she goes for Adelaide.
- As seen, the homeless guy's Tethered is so obsessed with Jeremiah "11-11" that he has carved the number into his forehead — or perhaps just a substitute for the lack of cardboard.
- The Reveal that Adelaide's Tethered successfully performed a Twin Switch with the original Adelaide as a child, with no-one save Jason being any the wiser. Red, whom we've presumed is a Tethered, is simply the original Adelaide reclaiming the life she should have had. Assuming from Adelaide's fear and feeling of Red returning before she appears and Red's acknowledgment of a Psychic Link between them that allowed her to find her way out of the Tethered tunnels, it's clear the real Adelaide knew the Tethered version of herself was not only happily living the life that was once hers, but somehow the Tethered and their Real counterparts can influence each other no matter the distance between them.
- What we see of the daily life of the Tethered is extremely unnerving. We see them passionlessly and silently going through the motions of what their counterparts are doing above at all times. One room of Tethered, for example, are silently walking around in circles while the people above are on a amusement park ride. Another shot shows the Tethered eating raw rabbit while the counterparts above eat, complete with squeals of pain and distress from the rabbits.
- Adelaide killing Red by impaling her and then viciously strangling her with a chain before her neck snaps very audibly. And then she starts laughing...
- The very last scene of the film, a huge tracking shot over the countryside which ends on a long chain of Tethered joining hands, with smoke rising and helicopters flying in the distance.
- When Red begins dancing after saying to Adelaide “If it weren’t for you, I never would have danced at all.” With the scare chord that accompanies her first movement, it’s enough to make the viewer’s heart drop into their guts.
- When Abraham unexpectedly roars during/after Red’s first speech. It’s so unexpected and sounds so inhuman.
- Zora's Tethered, Umbrae, is particularly creepy, due to the not-quite-normal smug smirk she sports during the whole movie. Even when she's dying — after having her back broken from being thrown into a tree from a speeding car, mind you — she's still grinning, and is even giggling. It's all downright disturbing.
- The "split diopter" shot used in the classroom scene keeps Red's face in focus even though she's practically touching the camera. It's incredibly unnerving.
- There is something deeply unnerving about the Grand Pas de Deux extended scene: the moment that the Tethered realize Red is from above is during a dance recital. The scene flashes between Adelaide performing graceful, elegant ballet and Red, despite being dressed in a tutu as well, performing something more akin to a borderline feral, violent interpretive dance, flinging herself to the floor and against the walls at times. Both of them are seen predominantly from behind and silhouetted, Adelaide against the pure white of a spotlight and Red against the grimy darkness of the hallway. Red ends her dance with a shriek full of rage and grief, flinging herself to ground one last time, where Adelaide ends in a graceful pose. Where Adelaide receives tumultuous applause, Red is suddenly surrounded by the soft sound of dozens, if not hundreds of footfalls as all the Tethered in the area gather around her...
- In one deleted scene
, Red sees what she thinks is her real parents, but then they close in on her very creepily and it's obvious from that point it's the Tethered version of her parents up above.
