Yeah, putting this in the fan section is a bit odd to me.
Anyway, in the
Hellsing manga, in the English version at least, in volume 8, there's a chapter entitled "Castle Vania 1".
(All the other chapter titles are references to other video games as well.)
In volume 9, the first chapter is simply titled, "Castle Vania". No obvious
Castlevania references in the series beyond that (that I can think of), unless you wanna count the name Alucard, which could have come from either
Dracula's Curse or
Symphony of the Night, but could also have come from the 1943 film
Son of Dracula or any other source that uses that name.
Let's not forget
The Castlevania Dungeon's own Weirdness Section, which compiles a lot of references. I seem to recall it mentioning the character Sex Machine from the movie
From Dusk Till Dawn, but maybe it was taken down because it's not quite an obvious, clear-cut reference, though the movie features vampires, and Sex Machine has a whip.
(Some light whip-action at around 5:30 of
this vid, and of course
here; he doesn't really use the whip much, if I recall correctly.)
There's an electronic/remix artist who performs under the name Le Castle Vania. One of the logos actually has the "Vania" part edited from the original NES logo.
There's this particular load screen in
3D Dot Game Heroes:
There are probably more
Castlevania references in the game I haven't got to yet. This game is constantly referencing and paying homage to old school video games and sometimes more current games. I fear most of the references go over my head (there are probably a lot pertaining to RPGs, which I've never had much experience with). I would have never gotten the joke about "From Cave" if my brother hadn't been watching me play when I got there. He's played
Demon's Souls, and told me how it was developed by From Software, and pointed out all the references to the game in the cave. Pretty funny. :D