At 6 minutes, Richard speaks only in French to Jean but, in later stories, she speaks perfectly good English.
At 23.07, Jean asks the landlady if she is Celine Frederique who sang "Hey! Hey! Hey!" for France at Eurovision in 1995.
Although that is the character's name, the actual entry in the competition that year was "Il Me Donne Rendez-vous" by Nathalie Santa Maria.
00:05:47 - The letterhead on the photos has "gendarmerie" spelled incorrectly as "gendarmerie."
Near the start, a cab-over vehicle smashed into a tree crushing the front end and killing the driver. Soon after, a tow-truck is shown pulling the vehicle away from the tree. The front end is not damaged at all.
At no point (in the first 3 series at least) does anyone call Jean Madame Blanc.
Perhaps the title was chosen before filming which had to be moved to Malta due to Covid thus few actual French actors have been used and more British characters so the storyline took a different direction.