Screenwriter Robert Alberdingk Thijm changed the threesome from the book into a foursome for the movie. Author Mano Bouzamour liked the change so much that he rewrote that chapter to include the foursome in the next edition of his book, stating that he regretted that he didn't come up with it himself.
Director Norbert ter Hall wanted to make this an adaptation that would have the approval of the writer of the book it was based on. He only agreed to do the movie with the cooperation of author Mano Bouzamour, and kept him involved in every aspect of the movie, from the script to casting to editing.