Hansel is diabetic, as a result of his experience in the gingerbread house as a child. In the original script, Gretel was also supposed to have an eating disorder, as a result of the same trauma, but this was not included in the movie.
The movie's cast featured two former Bond Girls,Famke Janssen from GoldenEye (1995) and Gemma Arterton from Quantum of Solace (2008), where the movies were made and released around thirteen years apart in the James Bond film franchise. Both had Ian Fleming-esque "Pussy Galore"/"Mary Goodnight"-like double entendre character names, which were "Xenia Onatopp" and "Strawberry Fields," respectively.
Director Tommy Wirkola got the idea to create the film, based on the adult lives of Hansel and Gretel in 2007, while at film school in Australia. After being discovered by Gary Sanchez Productions, Wirkola pitched the idea at a meeting with Paramount Pictures and won a contract.
When Ben is taking care of Gretel, he brings her porridge and says that it's "not too hot, not too cold, but just right," thus making reference to another classic fairy tale story, "Goldilocks and the Three Bears."
In an interview with Famke Janssen at Cannes 2011, she stated that she took the role as the head witch in this movie because she had to pay off her mortgage. Janssen has stated multiple times that since 2007, she was prepping her writing/directorial debut with Bringing Up Bobby (2011), where funding and distribution had gone through hard times, partly due to the 2008 economic crisis. She also had not done much acting in that period of time.
Producer Adam McKay said in 2010, "The idea is, they've grown up and they hunt witches. It's a hybrid sort of old-timey feeling, yet there's pump-action shotguns. Modern technology, but in an old style. We heard it and we were just like, 'That's a freakin' franchise! You could make three out of those!'"
The Augsburg in the movie is a very alienated version of the real Augsburg, located in Bavaria, Germany. Nevertheless, when the movie started in cinemas in Augsburg, the real mayor of Augsburg appeared in a short clip before the movie and told the audience that he instruct Hänsel and Gretel to take care of the witch problem in the city.
The notices with images of the missing children, and rewards being offered that are attached to milk bottles, are a reference to the campaign that started in the 1980s, where pictures of missing kids were printed on milk cartons.
Famke Janssen and Jeremy Renner have both starred as superheroes in Marvel films. Renner played Hawkeye in Disney's Marvel Cinematic Universe films and Jannsen played Jean Grey in Marvel and Fox's X-Men movies.
Jeremy Renner played Clint Barton/Hawkeye in the cinematic Marvel comic universe: Thor (2011), The Avengers (2012), Avengers: Age of Ultron (2015), Captain America: Civil War (2016) and Avengers: Infinity War (2018) and Famke Janssen played Jean Grey in the X-Men films.
The trivia items below may give away important plot points.
The film climaxes with a witches Sabbath on a mountain. This location may be inspired by the Blocksberg (original name "Brocken"), a mountain in Germany. It's famous for being a place where witches supposedly converged for Sabbaths and gatherings. These "Sabbaths" would usually contain feasts, initiations of new recruits into the coven, and orgies with the devil.