About 34 minutes in, when Philipe tries to close the window in Simone's boudoir, the whole wall shakes as he struggles with the window, indicating that it is a set wall and not a real building.
At the 44 minute mark, when the guard closes Simone's jail cell door as her attorney Francois walks out, you can clearly see the wood grain on the diagonal "bar" of the closing door, indicating that it is not a real metal cell door, but is instead a wooden set piece.