1) Much of the trivia and references sections are full of useless tripe, people not getting a "joke" is being treated as a mistake (Yeah, in Just Desserts the planet really can't fall out of orbit because of too many fat people! Thank you Doctor Scienceburgstein!!!!), or just people taking the show too damn seriously and other Enterbot-isms.
2) Parts of the image galleries have these inaccurate, made up, and often cringey quotes attached to them. If you're going to add a quote, and it should be an iconic one not every freaking thing that comes out of a character's mouth, then at least make sure its accurately spelled.
3) Some articles, especially character bios, are full of speculatory nonsense, or are otherwise just go on for way too long. I mean characters like Tootie and Trixie are my favorites, but they're characters who appear maybe once or twice PER SEASON and have articles that are almost longer than Cosmo or Wanda!
4) Don't even get me started on how horrible the formating of this wiki works when trying to view it on a phone or smaller than 1080p monitor... granted much of this wiki was built before smartphones took off but some parts of it are just outright broken. There are too many pages you could easily condense much of the wiki by merging things.
Maybe someone should adopt this wiki that is willing to do some major overhauling. Not me of course, I'm a drawslave so all my free time goes to that, but someone will definitely have to do some major page moving/deleting.