Douglas Sirk immediately left the Netherlands after the shooting. He never saw the movie.
Annie van Ees plays a 12-year-old boy. At the time of the shooting she was 45 years old.
Boefje is often mistakenly referred to as Wilton's Zoo, which is sometimes incorrectly cited as a title Boefje may have been released under in English-speaking markets. Wilton's Zoo was actually an entirely separate film project, prior to Boefje. Detlev Sierck told executives at the UFA Studios that he was traveling for location scouting for Wilton's Zoo as a cover story for his escape from Germany in 1937. Wilton's Zoo was never filmed.