Throughout the film, freeze frames of the original Le Projet Blair Witch (1999) footage can be seen on screen for a single frame, usually when a camera is turned on or off. Some of these include an image of a hanging stick figurine and the image of Michael standing in a corner.
Burkittsville officials took down most of the "Welcome to Burkittsville" signs before the film premiered, as many were stolen following the release of the first and second movies.
In order to make this sequel as surprising as possible, filming was done in complete secrecy in Vancouver, as opposed to Patapsco State Park where the original was shot. The film was originally promoted under the faux-title "The Woods". The first trailer was then shown at the 2016 San Diego Comic Con, revealing it as the third "Blair Witch" film, a mere two months prior to the premiere.
(at around 59 mins) Ashley (Corbin Reid) pulls "something" from her leg wound. There's some debate as to what it is amongst fans, though it has been confirmed to be a "root." The effect was done practically, without any CGI. In fact, besides digital removals, the film is almost completely free of computer effects.
The tunnel was fifty feet long and featured tight spots crafted to Callie Hernandez's shoulder width, giving it an extremely claustrophobic look. One camera operator had a panic attack and had to be replaced for the scene. When Callie became stuck, two other people were in the tunnel with her; one was holding her legs so she couldn't move forward, and the other was in front of her filming.