Instead of having two sons, the character played by Mads Mikkelsen was originally meant to have a son and a daughter, the latter to be played by director Thomas Vinterberg's daughter Ida Maria Vinterberg. However, Ida was killed in a car crash in Belgium four days into filming, before she was planned to film her scenes. The film is dedicated to her.
The film was based on a play Thomas Vinterberg had written while working at the Burgtheater in Vienna. Additional inspiration came from Vinterberg's own daughter (Ida), who had told stories of the drinking culture within the Danish youth. Ida had originally pressed Vinterberg to adapt the play into a movie, and was slated to play the daughter of Martin (Mads Mikkelsen). The story was originally "A celebration of alcohol based on the thesis that world history would have been different without alcohol", and according to Vinterberg, it was "a much angrier movie". However, four days into filming, Ida was killed in a car accident. Following the tragedy, Vinterberg stated that he considered to stop making the film, and even considered to "stop living". However, he eventually decided to rework the script to become more life-affirming. "It should not just be about drinking. It was about being awakened to life," stated Vinterberg. Co-writer Tobias Lindholm served as director in the week following the accident. The film was dedicated to Ida, and was partially filmed in her classroom with her classmates.
Denmark has some of the highest rates of teenage drinking in the world; a World Health Organization report released earlier in 2020 found that Danish 15-year-olds consumed alcohol at nearly double the European average. Recent efforts to raise the minimum age for purchasing alcohol to 18 from 16 have met with resistance, in part because older adults recall their own youthful intoxications so fondly.
According to Mads Mikkelsen, there was not any alcohol involved on shooting days. Yet off set, there was some experimentation on what specifically would happen at 0.05%, 0.08%... There was even a "little boot camp" to monitor how speech and movements changed. But for the "next crazy Charlie Chaplin level" the team watched a lot of YouTube videos.
Thomas Vinterberg and the four main actors often meet up and bond over drinks after filming scenes.