These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Awesome Music: The theme song used for the Stardust Crusaders OVA, a cover of "Holy Diver" by Ronnie James Dio (The first half of Dio's namesake), preformed by Killswitch Engage. The original is used at the end of Dio's proper debut episode as well.
Ensemble Darkhorse: Dio's hipster underlings steal the whole damn show, in the first PB episode.
Jotaro: Wow Dio, looks like I just violated your manhole..... cover.
Also gets lampshaded and defied when Dio's explaining what he did to Joseph.
Dio: I, Dio, blew any chance of him living out of the water. I, Dio, sucked him bone dry. I, Dio, reached around and— you're just getting me to say a whole bunch of really gay sh*t now, aren't you.
Jotaro: Heh heh, yeah.
Fridge Brilliance: The fact that D'Arby never gave up the secret of Dio's stand is probably because he went insane...but it could also be because he never called Jotaro's raise and basically folded. He never had to give up that information since he never put it up for wager in that game. As for why he freaked out more when it was brought up... he was probably scared to death about Jotaro's ability since it was possibly the power to stop time as well as the fact that Dio would probably have him killed for betrayal.
Joseph's remark about Jotaro being like the son he will probably never have is pretty funny, moreso when he mistakenly calls him Josuke (As in Josuke Higashikata.) It becomes even more funny when you remember that Josuke really IS Joseph's son.
Vanilla Ice's brief cameo in the last episode might just be for a one-off joke (Polnareff putting him "on ice")...until you remember that in episode 8, in this version (Using the OVA footage) Polnareff just stabs Ice and slashes his head in half, unlike in the manga where Polnareff exposed Ice to sunlight, which destroyed Ice's body utterly leaving nothing behind since Ice was a vampire. Since in the OVA and abridged series, Ice still had a good bit of his body, he probably survived and regenerated offscreen! Considering Dio was able to regenerate after being vertically cut in half in Part 1, it makes sense.
Why does David Carradine's ghost haunt Dio and mock him about payback when Dio is very nearly killed by a vampire? Because earlier, Dio cruelly joked about Carradine "dying during his research" much like Jonathan would have, but is now being menaced by a vampire that he, Dio, created with Stone Mask just to see if it works. In other words, Dio very nearly died during his research!
As noted on the main page, Carradine's real life death is popularly believed (but officially dis-confirmed) to have been related to autoerotic asphyxiation, and Dio is dying via a blood-drain that looks like choking and may or may not have been aroused by it judging by his comment after the vampire attacking him dies ("Way to blue ball a guy!")
George Joestar's ironic reincarnation becomes even more fitting when you know that karma can be traced back to the texts of Hinduism, a religion that forbids eating beef (and most cruelty to animals). Probably not the smartest choice for a guy who tortured cows.
Growing the Beard: Most fans agree that the series noticeably jumped in quality either on episode 4 or 6, depending on who you ask.
Harsher in Hindsight: Speedwagon after being hit by Zeppeli, states that he'll never have kids, which would explain things.
Hilarious in Hindsight: Speedwagon at the end of the comment special, commits that he has tanning oil in case of encountering half naked men. Years later, he meets the Pillar Men who all qualify for this.
Hilarious in Hindsight: The bonus video "Doppio was phone?" has a guy drunk calling Hirohiko Araki and asking if they would ever make another Jojo anime. It took two and a half years, but he got his wish.
Joseph's description of the picture he offers D'Arby is rather.... descriptive.
Joseph: That's a picture. Of me. Sitting on a couch. With my legs spread open. Naked. This picture was on the cover of GDILFs Magazine's 'Top Ten Sexiest, Most F*** able Grandpas. I was number one. Beating both Monkey D. Garp from One Piece, and Uncle Iroh from Avatar.
D'Arby: How...recent...is that picture?
Even more hilarious/disturbing is the fact that there really is a picture out there that matches that description quite closely, despite it being unlikely for Antfish to have inspiration for the joke from it.
N'Doul's death scene of all things, especially when the sad music starts up and N'Doul relates his tragic backstory to Jotaro. Sure it hits Mood Whiplash when Jotaro points out that said backstory was lifted from a flashback from Ray but it goes back to emotional when Jotaro buries him and wonders if they could have been friends.
An minor one in the Comment Special of all things. Dio's response to Jotaro's dig at the fact he has no real friends showed some serious insecurity. It becomes funny almost immediately afterwards, but it was clear Dio was actually pretty darn hurt by that observation.
Jotaro: You're a jerk...because you don't have any friends.