In France, when passing the driving license test, a new driver has 6 penalty points (at first, and then 12 after three years without point loss), which can be deducted for various infractions, like speed driving. Points can only be recovered by attending traffic safety classes.
Producer Patrick Godeau asked Jonathan Barré to make a movie about such classes, but Barré declined, because Coline Serreau made a famous documentary on this topic a few years ago: Tout est permis (2014). He liked the setting though, as these classes are open to everyone, meaning this is a way to meet people one would normally never meet otherwise.
Godeau insisted by suggesting making it into a genre movie, and only then did Barré had the idea of a revengeful serial killer working as an instructor for traffic safety classes by day.
The movie's working title was "Pas permis".
Veteran actor/director Olivier Marchal, who is specialized in cop movies, was chosen for the short but important role of Jean-Claude Lalouette, which made everyone happy as he has a very tight schedule and wasn't available for more than a day.
Writer/director Jonathan Barré was born in Brittany and feels most at home there. He chose to set his film there, but the story could have happened anywhere else, but during location scouting in Douarnenez, the crew loved it. Barré also found the idea of characters in movies uttering the word "Plouhinec" (the name of a local town) very funny.
Originally, Jonathan Barré cast himself as the dead fiancé, which is never shown onscreen except in pictures strewn around Pauline's house and car. But he realized this was an important character to which the audience would respond, so he went looking for a known actor who would accept to only be present through still pictures, and finally asked French comic Thomas Ngijol, who agreed. The production designer put as many pictures of him as she could in the sets, and Barré kept texting Ngijol during filming, telling him it was like he was shooting the movie with them.