At 1:17:26, while playing a game of chess, Maurice Sauvage (Jean Sorel) tells his opponent that he is going to lose his queen, notwithstanding the fact that the piece clearly has several positions to escape to.
When Helen finds the missing washer for her engine in Maurice's breast pocket, there is no explanation, other than maybe x-ray vision, that she should know it was there, particularly as Maurice would have been unlikely to fool around with her engine in a dress suit.