When Lord Raptor performs his special move, "Ultimate Undead", a small tune will sound which sounds strikingly similar to the introduction of Michael Jackson's song, "Bad".
Morrigan was originally a female vampire but the game's designer, Alex Jimenez, changed her into a succubus because they already had a vampire. Capcom didn't know what a succubus was but when Jimenez explained what one was, they were suddenly all for the change.
There is evidence in the code of the arcade version that the two boss characters, Huitzil and Pyron, may have been planned as playable at one stage of development. There is an alternate color scheme for both of the characters that shows up if you are playing a mirror match, both characters are able to be played in Arcade mode though hacking (though Pyron can't fight the final boss due to a bug), both of the characters have their own endings, which are the exact same as their endings in the sequel, "Night Warriors: Darkstalkers' Revenge", though in a more unfinished state with the ending text just repeating "A" and the music not playing like it should.
The game originally started out as a Universal movie monsters fighting game, which would use the Street Fighter II engine. Though the final game still uses the engine, Universal did not want to license the monsters out, meaning the development team had to make completely new characters, which producer Alex Jimenez said took him about an hour to do.