Since the Coen Brothers knew they only had two days to shoot their sequence and were working on a very tight schedule, they elected to mount it in a metro station just in case it might rain.
The original intention of the film was to represent each of the 20 arrondissements of Paris with 20 short films but two of them (the 15th arrondissement, directed by Christoffer Boe and the 11th arrondissement, directed by Raphaël Nadjari were not included in the final film because they could not be properly integrated into it.
This is the first feature film fully scanned in 6K and mastered in 4K in Europe (as opposed to the normal 2K). Encoding the image took about 24 hours per reel (at Laboratoires Éclair).