A hilariouis movie from 1965, starring William Shatner. Saw it recently and laughed my ass off. The whole film is entirely in Esparonto! Accompanied with hilarious english subtitles!
...not to be confused with the later, nasty little John Cassavettes film.
I've seen it. In fact, I have a review of it at my web site:
http://www.badmovieplanet.com/unknownmovies/reviews/rev140.html