It might be related to real - life tragedies that occurred in the theater. For instance, an actor getting seriously injured or even killed during a performance that involved some sort of hanging prop or set piece similar to a gallows. Another possibility is that it was inspired by historical accounts of cruel punishments in or near theaters in the past, which left a sort of haunted legacy. However, the movie also takes a lot of creative liberties and may not be a completely accurate representation of the real - life events that inspired it.
The movie 'The Gallows' was marketed as being based on a true story, but it's a bit of a stretch. It's a horror film that used the idea of a high school play gone wrong and a haunted gallows on the school's property. In reality, it was more of a fictional horror concept inspired by common horror tropes rather than a strict recounting of an actual event.