When Virgil talks to Claire about "seeing each other" the blue folder disappears between shots.
As Virgil passes through the glass-pane door of Night and Day café almost at the end of the movie, there is a sticker on the glass pane of the door which read "Pivnice U milosrdných" - the original Czech name of that pub.
At the restaurant which is supposed to be extremely high-end, a waiter puts down stacked plates with what can only be described as horrendous racket. He balanced the plates at an angle and almost dropped the whole structure. Not something that would or could happen in this kind of establishment. To avoid such a mishap a plate is slid onto the table from the edge so that it remains level at all times. Any noise made by plates or silverware is inadmissible in places like that. Even champagne should be opened quietly.