The scenes in the mine are filmed in Slade, Kentucky and you can visit it and take a tour of inside the mine. There are two different touring companies, The gorge underground & SUP Kentucky.
This movie is based on an actual event and town, which was also used as the basis of the movie "Silent Hill". A coal mine fire did occur in 1962 in Centralia, Pennsylvania. It is still burning and really will burn for many years to come. However, Centralia was not hidden behind fences in a mine pit. It was gradually evacuated, or in some cases, residents were forced to leave by City leaders due to the numerous cracks and sinkholes that kept occurring and made it totally unsafe to live in. Most of the houses and buildings were demolished and very little of the town remains, except for a main road which is covered in graffiti. You can walk through, however and see the smoke coming from random cracks. The creatures were probably inspired by the two "The Descent" movies.
Jonathan Sadowski, Nathan Phillips and director Bradley Parker previously worked together on horror movie Chernobyl Diaries (2012).
Producer Fancy B Rosende also produced Bad Friends pod with Andy and Bobo.