Hastings: It's a wonderful day. Just fill your lungs with that air! Poirot: No, my poor friend, this sort of air is intended for birds and little furry things. The lungs of Hercule Poirot demand something more substantial: the good air of the town!(00:26:00)
Plot hole: The hole in the hat was pre-existing and the bullet was fired in advance and dropped. Poirot notices immediately the hole when Nick puts the hat down but somehow missed it while she was wearing it as she supported him. He also does not notice that the bullet has not been fired at that time - which would have been still hot if just fired, not at all if dropped. Most importantly, in the spot where they were sitting, it's not even possible to think where a shooter could have ever been hidden; nobody wonders where the mysterious shooter could have been or cares to investigate the circumstance despite knowing the very moment the supposed shot happened. The fact is basically ignored throughout the rest of the episode.
Trivia: David Suchet performed all the various conjuring tricks Poirot is trying to pull off. The illusionist in the theater show at the beginning is the late Patrick Page, real life stage magician and coach/consultant for the episode.
Answer: He definitely says "Belgian", but the subtitles get it wrong and show him saying "American."
Wblank71