The "drugs" used in the movie included: inositol as cocaine, herbal tobacco as marijuana, rock candy combined with vapor from an e-cigarette as crystal meth, and a sugar/vegetable oil mixture combined with e-cigarette vapor when Erin freebases.
Cast/Crew members Chelese Belmont, Shannan Leigh Reeve, Kim Leblanc, Danielle Rayne, Preston Thomas, Ashley Love, and Lori Dean all worked at Universal Studios Hollywood prior to filming Penumbra.
The film was partially funded thanks to a successful campaign on IndieGogo in July-September of 2014. Chelese & Shannan managed to raise $13,000 to finish filming the last 50 pages and pay for a composer/post-production.