Something you thought was fake, but is actually real

The collaboration between Disney and Salvador Dali that was actually supposed to be a real thing in the 40s. It was later revived and completed in 2003 as the short film "Destino."

As a child of the pre-internet era, I only saw narwhals in cartoons. So I sort of assumed that they weren't real, like they were just unicorn whales.

I remember when looking at the "Club Joey" page on Creepypasta Lost Episodes Wiki and noticing that during one of Alfred Neuhauser's video logs (he's one of the creators of the "Club Joey" cartoon), he told a tragic backstory behind one of the disturbing images he put in one episode of the cartoon, where a girl from the 1900's was locked inside her room for a very long time by her strict mother due to the latter not approving the person the former fell in love with. When I looked at the TV Tropes page for the trope "Nightmare Face", the photo with the tragic backstory was included as an example and I was shocked that the event was real, since creepypasta stories were mostly just spooky stories loosely based on real life events or were entirely fictional. This is why I was interested in the "Club Joey" page, because the article was so good that it sounds believable, and who knows, maybe it was based on some weird actual cartoon with a similar premise that aired during kids' blocks on syndicated television.
Sadly, the article was deleted for some reason on the Lost Episode Creepypasta Wiki, but a mirror of it was made on Spinpasta Wiki with a few changes.
spinpasta.fandom.com/wiki/Club_Joey

its a sea creature, its gonna be the most suprising looking thing in the world lol

I watched that once in art class because we were studying surrealism, disney remade the animation later and it looks really good.

Ok so, in Psychonauts 2 there's an Easter Egg dubbed as "Pregnant Raz" (because that's.. what it's about) which is an animatic of a joke opening sequence made by the guy that made Adventure Time. I first found out about it through a YouTube playlist of Psychonauts memes as that was one of the videos including. I thought it was fake but not trying to be a hoax, rather I thought it was a joke, like "GUYS LOOK AT THIS TOTALLY 100% REAL EASTER EGG THAT'S DEFINITELY NOT FAKE" type of thing. When I followed the steps in the actual game I certainly did not expect to have it broadcast on the family television. Oh the horror

Vinny mentioned