(And to go back much more recently, apparently in the era of silent movies wiseacres took it upon themselves to fill in the dialogue themselves. Mel Blanc educates me!)

One of the awesomest Aussie movies of all times is based on this premise, unfortunatly Hercules Returns is now out of print (or whatever they call movies that you can no longer buy on video or DVD) http://www.imdb.com/title/tt0107103/