Aerial shots of Jean skiing behind a boat show the stunt double jumping the wake, and skiing, one-handed, far to the side on the open water, switch back and forth between close-ups of Jean-Claude Trintingant, but in the close-ups he is always in the wake, both hands on grips, directly behind the boat.
In the morgue there is a crucifix on the wall. It's impossible in France, where the story is supposed to take place. It shows the scene was shot in Italy.