The Amazing World Of Gumball "The Rex" (partially found material of unfinished episode of animated series; 2012)
In 2012, a list of episodes relating to the second season of The Amazing World Of Gumball was leaked online, among them was an episode named "The Rex" which later got scrapped due to financial reasons and the fact that the creators of the show thought that the episode was a complete waste of money.
Very little about the plot, if anything has been released on the internet except for a signal storyboard that's viewable on this page that shows dinosaurs attacking the titular character, Gumball and a ravaged city. Apparently, this episode will premiere as a less pricey version in the third season of Gumball, but the possibility of this being true is very low.
The storyboard for this episode could be found on Jean Texier's website, but it has since been deleted.