Continuity mistake: His Bankship visits Poirot during the evening, and begins telling him the story of the silver mine. "For half a century, men have died", he says. Poirot has the magnifying lens in the right hand, but also the rock in the left; cut to a different angle, the hand with the rock is held low, out of frame, and then back to the first shot, with the rock exactly where it was. (00:11:55)
Continuity mistake: Poirot opens the "intolerable" letter Miss Lemon hands him; camera in the door and he has his finger between envelope and letter, reverse shot and he is holding them parallel together. (00:33:45)
Continuity mistake: Poirot reads the telegram after the opium den raid. The letter is in his left hand, but moves between shots to the right hand. (00:40:40)
Answer: He definitely says "Belgian", but the subtitles get it wrong and show him saying "American."
Wblank71