9. The Cast Were Terrorised In The Woods For Real - The Blair Witch Project
The production of ground-breaking found footage film The Blair Witch Project is absolutely legendary, for as terrifically lived-in as the performances from Heather Donahue, Michael C. Williams, and Joshua Leonard are, that's in large part due to the film's unorthodox shooting style.
The three actors spent eight days in the woods without direct contact with filmmakers Daniel Myrick and Eduardo Sánchez. Rather, they were guided by clues and instructions left in milk crates which the trio found with a GPS device provided to them.
Myrick and Sánchez arranged for the actors to walk long distances during the day, while at night the crew would enter the area and terrorise the performers and even steal some of their food.
This contributed to the actors' genuinely frazzled mental state throughout the duration of the shoot, and though their safety was being monitored from afar at all times, the sheer uniqueness of the acting assignment surely contributed to the stirring believability of the performances.
This formula has since been emulated in countless other found footage films, but never again this successfully.