Is there a translation of the Monty Python quote "And now for something completely different" that is actually recognized by some French speakers as a reference?
I don't know of any official translation. I'll propose et maintenant, sans transition (literally: “and now with no transition” [to ease the change of topic]). It, like “and now for something completely different”, was a catchphrase of a TV presenter (maybe not from the same generation) used as a transition phrase between two topics in a TV program. I think that presenter was Patrick Poivre d'Arvor, who presented the TV news program with the largest audience in France for two decades, though I don't know whether it originated with him. The phrase gets a lot of use, I think most French people today will recognize it as something they've heard before (even I do, and I've probably never watched that news program).
The series has been dubbed La première folie des Monty Pythons (The Monty Pythons' First Folly), but the original title is almost always used as far as I can tell. As far as I know, there is no official translation of the phrase itself ; I have actually seen it used as is in French (granted, from English literate persons).