The movie was shot in 15 days. The very last thing shot was the burning house. Because of the films shoe string budget, only the camera team was scheduled to shoot the fire, but the entire crew volunteered their time to come out and work a 16th day because they felt the fire would be the ultimate wrap party.
Every number in the film has a digital root of 3, 6 or 9. This includes any date referenced in the film, numbers on documents, or numerical values. Directors Alex Lee Williams and Jay Drakulic hand wrote every single document of evidence, newspaper article and written prop themselves to ensure that the "9 theory" was represented properly.
Hellmington was the winner of the 2015 Cinecoup Film Accelerator challenge which grants $1 Million in financing. Over the course of 10 weeks, filmmakers pitch their film ideas through a series of challenges that occur at the beginning of every week. By the end of the festival, 5 are chosen to pitch the film to a panel of industry professionals at the Banff World Media Festival. The original film concept was a Fictional Horror Documentary that focused on the missing case of Katie Owens, but after the film won the competition, the studio decided to re-focus the story with as a narrative.
During one of the shoot days, a tattoo artist came to set and tattooed the Revenien symbol on many crew members to symbolize the significant bond that formed on set. The set where this occurred was in fact Sam Woodhouse's family kitchen from the beginning of the film.
Many of the key crew members on the film opted to live in a house together during the entire duration of filming. This allowed for more work to be completed after hours and on off days due to the intense shooting schedule.