Blair Witch (2016)

Trivia: Spoilers: At one point during the climax, you can briefly see a creature with long arms and legs barging through a doorway for a split-second. Many viewers assumed that this was the titular "Blair Witch." However, the screenwriter has stated that any creatures/specters visible in the film are meant to be grotesque manifestations of the witch's past victims (with the long-limbed creature presumably being Heather given she's in the place where Heather died), and that as stated earlier in the film by one of the characters, nobody can actually "see" the witch herself.

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Trivia: A somewhat comical behind-the-scenes fact: During filming, in order to get the actors to jump and act scared at the right moments, director Adam Wingard would occasionally secretly carry around an air-horn and "honk" it when the actors weren't expecting it. (And then obviously dub over a scarier sound effect in post).

TedStixon

Trivia: In order to maintain secrecy, the movie was shot under the working title "The Woods." Posters and promotional material for the film under this false title were even made and distributed to some theaters and festivals before the real title was revealed.

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Lisa Arlington: Okay, so the Blair Witch. Who is she really?
Talia: Elly Kedward. That's what most people say. She was accused of witchcraft after some of the children in town said that she'd taken blood from them. There wasn't much of a trial system back then. Townspeople took her out to these woods, tied her to a tree and left her to die of exposure.