The dry clothing of Roger and Costa as they emerge from the halfway filled vine vessel.
During the last seen in the house, when Belmondo kills the last guy with the shot-gun a rope can been seen while falling off the window.
Gilbert (l'Epervier) is supposed to live in Juvisy-sur-Orge, but his house is really standing in Carrières-sur-Seine.
The fight at the end is pointless. Even if Cremer managed to kill Belmondo, his identity as the "hawk" was revealed anyway and he couldn't escape from the plane.