Whilst I was in Prague, I was lucky enough to watch them film a scene in the movie. It was being filmed on the street I was staying on.
They had converted the entire street into a Parisian rue. I guess it's cheaper to film Paris in Prague, than it is to film Paris in Paris.
It took them 3 days to film 20 seconds of footage. By the end of it, the whole street looked like it had been blown up. They had set up a florist, a boulangerie and what not. All destroyed.
Regards,
Humayun