When first visiting Professor van Blankenberg, Antoine Lemercier and Charles-Hubert Pochet pass by the fragment of statue (legs and left arm) that they will eventually discover at the end of the movie.
When the three are jumping on the roofs they had usually to sweat because it is summer in Greece. But they didn't sweat.
In the scene when a man tries to throw Lise out of the train you can see that the nature out there is a screen.