Each sequence of The Forbidden Room is based on reviews and summaries of "lost" films, mostly from America in the early to mid-20th century. These films were destroyed intentionally or by natural degradation of the original film stock, and will likely never be seen again. Guy Maddin realized the only way he'd be able to see these lost movies was to make them himself.
This project was originally conceived to be a series of stand-alone short films. The only way Guy Maddin was able to receive enough funding was to string some of them together into a feature.
By title designer Galen Johnson's estimates he created 500 intertitles for the movie, of which 400 are seen in the finished film. He also had to essentially make them twice for the French language version of the film as well. He used Adobe After Effects as well as Photoshop and Illustrator for the custom designed typefaces.
Co-director Evan Johnson stated in an interview with Matt Prigge in 2015 that the multi-layer film structure (nesting doll structure), was because he received influence from late french novelist and poet Raymond Roussel (1877-1933).