Newly wed, Bill Pullman's wife was invited to be an extra and appears on screen as the blonde who pushes a long needle through a willing man's cheek.
Due to political strife and civil turmoil in Haiti during the production, the local government informed the film crew that they could not guarantee their safety for the remainder of the shoot. The crew subsequently relocated to nearby Dominican Republic to complete filming.
The character of Christophe Durand was based on Clairvius Narcisse, who was stated to have died in 1962 and was later risen as a zombie by a local Haitian witch doctor. Narcisse was poisoned by Datura, a drug which caused memory loss, and forced to work as a slave on a sugar plantation. He escaped 16 years later, after his captors had died. He had apparently been weaned off the Datura by eating salty foods containing bromide, which counteracted it.
Author Wade Davis agreed to sell the book rights on the condition that Peter Weir direct and Mel Gibson star. Neither man had any involvement in the project.
The actual investigations and findings of Wade Davis, upon which the character Dennis Alan is based, didn't amount to much. Davis's research was mostly dismissed by his peers, while the drug tetrodotoxin (which the film states has been under extensive study and was a mystery to science) was actually already well known in 1985 and today is used as an anesthetic.