Author Existence Failure: Not death-related, but many scripts and concepts that John K. pitched to Nick before Spumco was fired were later finished or adapted by the Games crew. Among the episodes fully realized at Games include: "A Yard Too Far" (John K. pitched this as a remake of the Yogi Bear cartoon "Pie Pirates"), "Magical Golden Singing Cheeses" (it was originally meant to be a Stimpy's Storybook Land outing), "Stimpy's Cartoon Show" (Wilbur Cobb was originally visually different than how he turned out, among other changes), and "Ren's Brain".
Creator Backlash: John is actually pretty critical of the original show, and he warns his fans not to study his cartoons—"For everything we did right, there were a ton of mistakes."
He also hated "Nurse Stimpy" and "Fire Dogs II". The former for all the cuts Nickelodeon wanted and many artistic failings, the latter for its deplorable timing and sluggish pacing, although he admitted it had good characterization.
John K dislikes many of the Adult Party Cartoon episodes, both due to the adult content he was asked to include but didn't really want to and their slow pacing.
Billy West absolutely refuses to work with John Kricfalusi ever again because of how much of an insufferable prick Kricfalusi is.
Executive Meddling: Nickelodeon messed about with this show extensively due to censorship issues and John K's inability to make deadlines. When John K. complained, they fired him. Then he revived it for Spike TV... where the inverse happened. He could never catch a break.
John K's firing is a controversial topic subject to much debate. Some comments from Billy West and Bill Wray seem to lean towards the idea that repeated Schedule Slips did John in.
Characterization also was affected, since John K was allegedly asked to place more genuinely heartwarming moments in the series as well as make Rena more ultimately kind intentioned character. Ironically these elements were mostly depleted after John K left.
God Does Not Own This World: Probably one of the most Shakespearean and operatic instances of this trope, since Bob Camp, Chris Reccardi, Bill Wray and other Spumco-ites from the first two seasons chose to stay with Nickelodeon and the show after Kricfalusi was fired.
Keep Circulating the Tapes: The short "Chicken in a Drawer", which was absent from the second DVD set, likely due to using time-compressed Spike TV masters. Speaking of Spike TV masters, a large number of episodes on all the DVD sets of the original series featured cuts, ranging from only a few seconds to a minute in some instances. This was due to Nickelodeon tampering with footage from the negatives after Kricfalusi's firing for the reruns of them. Although he got the episodes as close to the originals as he could for the sets, he couldn't get all of the original footage back.
The Other Darrin: Billy West replaced John Kricfalusi as Ren when Kricfalusi was fired, which is funny because West originally auditioned to play both Ren and Stimpy when the show was in pre-production. West also took over as the voice of Mr. Horse and Mrs. Buttloaves following Kricfalusi's termination.Note
For the record, West began as Ren during season 2, as certain episodes during that time were finished by the Games crew (and thus, were in various stages of production, including voice acting). Examples of season 2 episodes where West voices Ren include "Monkey See, Monkey Don't", the oath segment in-between "Stimpy's Fan Club", "The Great Outdoors/The Cat That Laid the Golden Hairball", and a few random lines in "A Visit to Anthony".
Gary Owens replaced Darrin J. Sargent as the voice of Powdered Toast Man after the first PTM bumper.
Eric Bauza replaced Billy West as Stimpy in "Adult Party Cartoon" due to West being involved in other projects and wanting nothing to do with John K. or Ren and Stimpy after the 1990s.
Harris Peet originally voiced George Liquor in "The Boy Who Cried Rat" (in the short scene of George chasing Ren and Stimpy away from his trash) before being replaced by Michael Pataki.
In the Mexican Spanish dub of Adult Party Cartoon, Igor Cruz replaced Alfonso Obregon as Ren halfway through, and Stimpy was recast from Jose Luis Orozco to Jorge Ornelas.
Schedule Slip: Often cited as one of many causes of Kricfalusi's firing, while others claim that it was a smokescreen to get rid of him to placate offended advertisers. However, it did eventually get to the point where The Simpsons was making jokes about it (which is really odd, as later, John K. would create a couch gag for The Simpsons).
Talking to Himself: Both main characters were voiced by Billy West after John Kricfalusi, Ren's original voice actor, was fired.
Un-Canceled: "Adult Party Cartoon" (though most disappointed fans wouldn't count this).
What Could Have Been: Obviously, if John K. and his team hadn't been fired. Word is that season 3, had Spumco been kept on, would've mixed in more dramatic outings (similar to "Stimpy's Fan Club" and "Son of Stimpy") with the comedic shorts. Given how good they got at visual acting towards the end of their work on R&S, that would've been interesting to see.
Episodes like "A Visit to Anthony", "Fake Dad" and the aforementioned "Stimpy's Fan Club" were only partially finished when Spumco was fired and were mostly completed by Games. How much better these episodes would have turned out if John K. had been able to finish them is unknown.
In 1993, Nickelodeon was planning on making a Ren and Stimpymovie, along with a movie of Rugrats and Doug. Only the Rugrats and Doug ones were made (Albeit the Doug movie being made after it was bought by Disney), with the Rugrats one being successful enough for a string of sequels.
Billy West was supposed to be the voice of both Ren and Stimpy when the show first started. He got his wish when John K. was fired and Games Animation came in to make episodes.