As for individual levels, Big Bruty, from the Sega CD and Windows 95 versions of the original, gets this, even being excluded from the HD remake. And then there are the speeches, which serve as alternate endings in the Sega CD and Windows 95 versions as well.
Hell, The Special Edition itself is hard to find as well! Even if you do find either version, good luck playing them; modern operating systems won't run the Windows version, and Sega CD version is worthless without the Sega CD itself! The worst part is that this isn't the version that was re-released on GOG or Steam!
With the imminent shutdown of the Wii Shop Channel, not only will the Virtual Console versions of the first two games be unobtainable by normal means after March of 2018, once it shuts down entirely in 2019, even redownloading already purchased copies won't be an option.
Earthworm Jim HD was delisted from all consoles in February 2018, so unless you previously downloaded it, you're out of luck.
Port Overdosed: The original game. Not only was it ported to every contemporary system, including handhelds, but it has been almost continually re-released since then.
Posthumous Credit: The second game credits was dedicated to Mike Pilotti, who was killed in an avalanche.
The first game was originally about a character named SNOT, but when Doug TenNapel was hired on he showed his earthworm character and that stuck. The idea for a snot based character was put in the sequel.
A PSP game was planned, and apparently almost done, but due to financial difficulties, it was cancelled.
Plans for a TV show comeback and a feature film were announced with the 4 game but nothing ever came from either one.
Sega also considered the possibility of putting a port of the Sega Genesis/Mega Drive version of the original on Xbox Live Arcade, and made a poll with some other games to see people's opinions on whether it or other games should be on there. They abandoned the thought and replaced it with another game when they found out that Gameloft was already working on an HD remake for the same service.
Both Doug TenNapel and David Perry initially served as minor consultants for Earthworm Jim 3D, but were dropped for unknown reasons. One can only wonder how it would have turned out had they stayed.
International Coproduction: Between the US (Universal) and the UK (Flextech, who ran The Children's Channel, the first European kids' cable channel and one of the earliest worldwide, only being beaten by Pinweel/Nickelodeon) by seven years ('77 to '84).
Keep Circulating the Tapes: There were actual official release VHS tapes back in the mid-1990s (with select episodes), but with DVD becoming more popular than VHS, this petered out real quick.
The American DVD release which didn't even include the extras from the VHS tapes was put out by a company known for supply issues.
Production Posse: Doug Langdale began his association with Jeff Bennett here; on a producing scale, Universal and Playmates had previously collaborated on Exo-Squad, and Playmates also made toylines for many other Universal properties during the era.
Talking To Herself: In the episode "The Exile of Lucy", Queen Slug-for-a-Butt is deposed and sent to Earth, where she meets and befriends Mrs. Bleveredge, with whom she shares a voice actress.
What Could Have Been: Playmates Toys' tie-in action figure line went out of production before Professor Monkey-For-A-Head (among other characters) got released, much to the dismay of children and nerds everywhere.