The movie is based on the real-life friendship between Anne Frank and Hannah Goslar. Director Ben Sombogaart has stated that he frequently visited the real Goslar, who was in her nineties and living in Israel, to hear her story. She urged him to finish the movie as fast as possible, as she was in relatively poor health and desperately wanted to see it before her death. Despite delays in production due to the COVID-19 crisis, Sombogaart was able to show the finished movie to Goslar and her family, who all loved it.
Filming was done in the Netherlands and Hungary. Shooting of the concentration camp scenes had commenced in Hungary when the 2020 Corona crisis hit Europe, so all filming had to be stopped immediately. However, production could be carefully resumed a few months later with the help of a 'social distancing coordinator', in order to prevent further spread of the Corona virus.
Director Ben Sombogaart felt that the film's subject of antisemitism was still relevant, referring to an experience on the set when actor Roeland Fernhout wanted to walk off the Hungarian set to do some shopping. The Hungarian crew strongly urged him to take off his coat because it carried a yellow Star of David (the 'yellow badge' that the Germans forced Jews to wear to identify them as such), which could get him in trouble.
When Hannah's father is first shown, he is downcast. During the meal at the table, he says in Hebrew, 'Gam zu le tovah,' and the subtitles read, 'This, too has a reason.' It actually translates to, 'This, too, is for the good.' It is a famous saying by R' Nahum Ish Gamzu, a well-known sage in the Talmud.
Director Ben Sombogaart initially hesitated to make this movie. He originally wanted to make an adaptation of Anne Frank's diary (famously published as 'The Diary of Anne Frank'), since it had been adapted before but never as a Dutch movie. However, only the rights to the original censored version of the book were available, which was published by Anne's father Otto Frank after the war and omitted some sexual references and personal issues, which Sombogaart found too restrictive. He decided to adapt the story of Anne's friend Hannah Goslar instead, since the movie could then focus on Frank's friendships rather than her famous years of living in hiding. He was also fascinated by the parallels between the persecution of the Jews during WW2 and the refugee crisis of the 2010s.