Marie's and Nicolas' head positions and facial expressions don't always match up between camera cuts outside the theater.
When Nicolas and Marie by accident run into Francis at the Vietnamese restaurant, Francis introduces Nicolas to his friend Antony. However, in the first scene of the movie you can see that Nicolas already has met Antony as they all sit at the same dinner table. There is nothing to say that either Francis didn't realize they knew each other, or that Nicolas and Antony were merely playing dumb and avoiding an awkward situation.