The very first scene writer Emerald Fennell thought of was a female character lying on a bed while someone takes her pants down, as she is drunkenly asking "What are you doing?", then asking the same question in a completely sober manner. She wrote the rest of the film based on this idea, and the full scene did end up in the finished film.
The title is likely a reference to Brock Turner, a Stanford University student who was convicted of sexual assault in 2016. The judge sentenced him to only six months in prison on the basis that he was a "promising young man."
The words "rape" and "sexual assault" are not spoken in the film.
In an interview, Emerald Fennell said that Carey Mulligan was very nervous about having to act drunk, a notoriously difficult thing to do. Fennell reminded her that she wasn't actually acting drunk, but rather was playing a character that was sober, pretending to be drunk, so it didn't need to be perfect. This helped Mulligan relax, and Fennell was quick to point out that her drunk acting was very good.
A few months before the film debuted at Sundance, writer/director Emerald Fennell and her producers set up a test screening to gauge the reactions of a wide audience. During one of the scenes, a fight started between two audience members. One person was very angry about the scene, and the other person was telling them to leave if they didn't like it. She told IndieWire about the incident: "It was quite visceral and that was quite shocking because obviously I wanted to make a film that was thought-provoking that people talk about, but I wasn't expecting that."