Even the trailers for the show are EXTREMELY unnerving and creepy, featuring surreal or disturbing imagery as well as warping electronic music.
The trailer for the first series begins with a couple kissing, before zooming out, showing them on a screen within a screen within a screen, etc. Several of the scenarios that appear are somewhat unsettling — what looks like a porn film setup, a dark figure swiping through endless screens, a screaming woman gagged and tied to a chair... The list of wrong goes on.
The picture abovenote for vision-impaired readers, it's a distorted image of a woman smiling while holding a phone, 'cracked' in such a way that it appears her friendly smile is twisted into an unnatural, demonic grin appeared on a billboard for the second series. Imagine seeing that on your way to work every morning!
The second series trailer is arguably much worse — beginning as a riff on Apple and gadget adverts, it has a 'wrong' vibe from early on, thanks to a digital voiceover not dissimilar to that in the Radiohead song "Fitter, Happier". However, it soon gets plain disturbing...
Some of the imagery in that trailer includes: a strange symbol carved into someone's back; a wild-eyed man staring DIRECTLY at the camera; a man beating a tramp to death for a filming crowd; cracked and distorted faces; a bus and assembly line populated with masked, hooded people; a man either lacking eyes or with skin-colored eyeballs; and a crowd of people passively filming a huge cloud flooding the street in front of them, before ending with a small girl vanishing into the cloud...
The voiceover doesn't help: the computerised tone is very Uncanny Valley, and then it starts to break down entirely, finishing with the chilling "BE. YOURSELF. NO. MORE."
The fake smiley-happy people in the 'nice' bits don't help either. At one point, we see a woman and a baby talking with a man through a FaceTime-like app on a tablet computer. It's all very shiny and happy and nice. Then later in the trailer, we see another shot of the woman and the baby. The baby is crying, obviously upset or frightened at something. The woman? She's still smiling... but it's a very glassy and frozen fake smile.
The most terrifying trailer would arguably be the Netflix Vista trailer. In this promotional advert, the viewer is treated to a world where the eye-camera technology is used to stream Netflix. Random citizens are seen watching various episodes of Black Mirror through their eyes, while riding the train, waiting at the airport, standing by the sea, talking to a parent on their deathbed, all the while bearing frozen smilesand vacant white eyes. At the end of the trailer, when one man turns off the stream and comes to the dinner table with his wife, she is watching... so he just turns his stream back on. Nothing out of the ordinary happens, and that's what makes this trailer so scary.