Contest Winner Cameo: Done at least twice. The first time, the contest winner had his spleen ripped out by John Tesh after he requested it, feeling that it would be an honor. The second time, the contest winner's soul was sold to the Devil by the hosts in exchange for the souls of the Backstreet Boys and *NSYNC, who fans had requested to fight each other (they had both been killed in previous matches — the Backstreet Boys by the Beastie Boys, and *NSYNC by KISS).
Keep Circulating the Tapes: iTunes has made all the episodes of the revival and over a hundred fights from the original run available, but still, nearly half of the material from the first four seasons (including almost all of the commentary and storylines between the fights) can't be accessed legally. Fortunately, a lot of the stuff has been put back up on YouTube after Viacom's lawsuit against them failed.
To make things better, there are only three CDM tapes released (to this troper's knowledge): a supposedly "Greatest Hits" tape (consisting of 7 fights that are far from the show's "greatest hits"), and two compilation tapes (called "Celebrity Deathmatch: Round 1" and "Round Two").
McLeaned: Stacy Cornbred suffered from spontaneous human combustion after her voice actress left the show.
The Other Darrin: During the 2006-07 revival, Johnny Gomez, Nick Diamond, and Mills Lane were all recast. In Mills' case, his voice actor (Mills Lane) had a stroke and couldn't reprise his role.
Uncanceled: Sadly, this is one of those cases where the show should have stayed canceled, because it was a mess when it came back.
Unintentional Period Piece: One of the best examples of this trope. From promoting Anna Kournikova and Elizabeth Hurley as the internet's top two pinups, to billing the long-separated Bruce Willis/Demi Moore and Tom Cruise/Nicole Kidman as two of Hollywood's biggest power couples (back when not many people knew Ashton Kutcher or Katie Holmes, even), to featuring a fight between Bill Clinton and Kenneth Starr to finally settle the Lewinsky scandal, it is impossible for Celebrity Deathmatch to escape the turn-of-the-New-Millennium time period in which it aired. The show's pop culture reference-based humor is extremely dated and many of the celebrities featured are now far past their fame. To Millennials who don't have a decent understanding of late-1990s pop culture, this show is a hard watch.
The relaunch that aired on MTV2 likewise dates itself to the mid '00s, and will likely see the same fate as the original series. The first episode alone is built entirely around parodies of the long-canceled and largely forgotten shows The Simple Life and Viva La Bam, while other fights are about such Turn of the Millennium ephemera as The Osbournes, Pimp My Ride, Ali G, crunk rap, Britney Spears' public meltdown, and the Major League Baseball steroid scandal. One fight did reflect how the aforementioned Bruce Willis and Demi Moore had broken up... with the fight being between Willis and Ashton Kutcher, Demi's new lover (a relationship that ended in 2013).
What Could Have Been: To think that this show's glory years were before the rise of Reality TV, gossip blog culture, and celebrities who got famous through social media and YouTube... and what's worse, the revived version that aired for a brief time didn't even cash in this. Who knows what we could have seen if the revival was done well enough to stay on the air for more than two (nine episode long) seasons?
At one point during the show's first run, there was talk of a movie.
The Scifi Spectacular episode was to have a battle between Captain Kirk and Captain Picard. However despite even the approval of William Shatner himself, Paramount (a sister company of Viacom) pulled the plug on the idea because they weren't happy with the creators mocking their "million dollar franchise". Still it wasn't all bad, we ended up getting Nick Diamond's popular fight against Zatar the Alien instead.