The movie is based on the book "The Reincarnationist Papers" by D. Eric Maikranz. He found it difficult to catch the attention of a literary agent that would sell the book to Hollywood. On the first page of the book, he offered a commission to anyone who could get his book into Hollywood. Eighteen months later, he got an email from a Hollywood assistant director who found his book in a hostel in Nepal. In 2017, Paramount Pictures bought the rights.
Bathurst asks Evan, "Which of these items are yours?" which is the same test given to potential reincarnations of the Dalai Llama.
The Bathurst Estate is Highclere Castle, the same estate used in Downton Abby.
The car the Believers exits at the casino is an Aston Martin Lagonda Vision Concept vehicle.
The car chase that continues after they break out of the police station was filmed on Newport Road, Cardiff, South Wales UK