While shooting Season of the Witch (2011), Nicolas Cage and Ron Perlman developed a close friendship, which led Cage to accept this movie as an opportunity for them to hang out.
Matt being extremely old is a running theme throughout the movie. Even Ron Perlman's character Bobo emphasizes it. However, in reality, actor Ron Perlman is older than Nicolas Cage by fourteen years. Perlman was 73, and Cage 59.
Grace Byers, who plays crime boss Hector, was actually raised in the Cayman Islands, where this movie takes place and was filmed.
Towards the end of the movie (at 1 hour 33 minutes) there's a Wilhelm scream.