Character Vader Keller is from Surinam and believes in the Winti religion that's why he does what he does in the movie.
Surinam is a former Dutch colony and in The Netherlands live a lot of Surinam people. Thats why writer Leon de Winter chose this religion and superstition.
American Roy Frumkes and Dutchman Richard Abram set up a development company in the late 80s and developed two genre projects: 'The Subtitute' and 'The Johnson Blues'. Eventually, Abram decided to go back to the Netherlands, meaning the company was dissolved. Frumkes kept the rights to 'The Subtitute' and Abram those of 'The Johnson Blues'. This is why the film was eventually produced in the Netherlands.
Roy Frumkes original idea set the story on a camping trip in New York, with a clan of inbred hillbillies attacking a father and son. Frumkes imagined Clint Eastwood in the lead. When screenwriter Rocco Simonelli was asked to do a rewrite , he changed the main characters into a single mother and her daughter. Glenda Jackson was approached to play the lead and she suggested Oliver Reed for the part of 'Unk', the leader of the blue-eyed Johnson clan.
Ruud van Hemert was originally hired to write and direct. But when the producers didn't like the direction he was taking the film, Van Hemert was replaced with Rudolf van den Berg who was allowed another rewrite.
Liz Snoyink was considered for the lead role but eventually Monique van de Ven was cast. Van de Ven was the only cast member already in place when Rudolf van den Berg took over as director.