Eagle-eye viewers may have noticed the blue meth from Breaking Bad appeared in one episode in the series, The Walking Dead. Many fans believed this proved the two shows existed within the same universe. Some people went so far as to devise theories suggesting that Walter White somehow caused the zombie outbreak! According to the creator of The Walking Dead, this Easter egg was simply a bit of fun and shouldn't be taken too seriously.
Now, fan-theories like this are nothing new. Almost every popular show has had a fan-theory in one way or another. The Rugrats are all in Angelica's mind. Scooby Doo and the gang are on the run to avoid being drafted into the army. The Flintstones takes place in a post-apocalyptic future.
But once in a blue moon, a fan-theory is bang on the money and the creator of the show actually confirms it. Sometimes, the theory is validated in an interview with the creator. Other times, it is confirmed in the show itself. Although it rarely happens, there are a handful of times when a fan-theory is more than speculation and conjecture.
10. Adventure Time - The Story Takes Place After A Nuclear War
Adventure Time tells the story of a boy called Finn and his magical dog, Jake, going on wacky adventures in The Land of Ooo. Throughout the show, the characters repeatedly refer to a cataclysmic event called The Great Mushroom War.
At first, the name of this battle didn't stand out since everything else in the story is just as odd and random. Throughout the series, Jake turns into a brick, Finn encounters a spanking goblin, and Gunther the penguin is revealed to be a space god. Calling a battle "The Great Mushroom War" sounds pretty tame compared to the rest of the show's weirdness.
However, some fans believed that The Great Mushroom War was so-called as a reference to the mushroom clouds created by nuclear bombs. So, this wasn't some silly little fight where people were throwing fungi at each other. It was a nuclear holocaust which decimated the world.
But here's the coolest thing about this theory. The creator of the show, Pendleton Ward, never intended The Great Mushroom War to reference a nuclear fallout. However, he thought this fan-theory was so amazing, he incorporated it into the show.