Allegro Non Tropo is more like Fantasia than any other films discussed in this thread
https://www.imdb.com/title/tt0074121/?ref_=nv_sr_srsg_0
Bingo. Better than Fantasia. My favorite but very sad scene: https://www.youtube.com/watch?v=APSEYn7CqzQ
Yes, I immediately thought of Allegro non Troppo, as it is specifically a spoof of Fantasia. I don’t believe that it carried an R rating, but it does include some animated nudity.