Designated Villain: In The Betrothal, it's never specified why the Sick Man is so wicked. Nothing is said about his life beyond the fact that he was very sick, and his one fault in the actual play is picking Aimette for Tyltyl's future bride while the noble ancestors don't agree with him. Unlike the Rich Man, the Sick Man doesn't push Tyltyl for a Gold Digger marriage, and unlike the Drunkard and the Murderer, he doesn't attempt to grope Aimette himself. Nevertheless, he is treated as though he is as despicable as the other three Black Sheep ancestors.
Sequelitis: There is a sequel called The Betrothal, about sixteen-year-old Tyltyl finding his true love. It is... less known than the play, to put it mildly.
1940 version
The Production Curse: Several of the actors died shortly after movie production ended.
Visual Effects of Awesome: The scenes of the boat sailing off on the horizon and Light disappearing are absolutely stunning to watch, even today. Plenty of Scenery Porn is in effect as well.
1976 version
WTH, Costuming Department?: Water's costume looks like little more than blue rags, and Tylo's costume is a ratty brown dog suit that leaves only the face visible. (It's possible that the latter was thrown together in a hurry when the original actor had to be replaced.)