Because of the students' rebellion and strike that paralyzed Paris in May 1968, the movie producers moved to Brussels to film the major scenes (June-July 68). For example, it was possible to use the Superior Court building and transform the ground floor into a Paris railroad station with fake trains and a waiting room and all the other accessories.
In several interior scenes, Rock Hudson's hair style and sideburns are drastically shorter than in the rest of the film. This seems to give credence to the rumors of studio interference and the necessity of re-shoots.