The actor who played the policeman who only spoke French really did speak it as his native language. The actor who played the policeman that spoke French and German spoke German as his native language. The actor who spoke German and Spanish spoke Spanish as his native language.
During the Ricardo/Mertz trip to Europe, the American Express Office was mentioned many times, usually by Fred. In this episode, the actual Paris American Express office at Rue Scribe and Rue Auber is seen, presumably in stock footage. American Express is still located there (as of 2016).
The cafe patron with the goatee who toasts Lucy in the sidewalk cafe is actually writer Bob Carroll Jr. He sits at a table with writer Madelyn Pugh, who is just out of camera shot during the toast.
Lucille Ball's camera and lighting stand-in Hazel Pierce, is among those in Fred and Ethel's tour group.
Following this episode, Lucille and Desi did a 30 second public service announcement for "Heart Month". The couple were stalwart supporters of the Heart Fund of the American Heart Association. Ironically, Lucille Ball died of an aortic dissection, a heart-related ailment.