List of references on the Internet

Homestar Runner
On homestarrunner.com, there is a toon called "Pumpkin Carve-nival". In it, The King of Town is dressed as Mario. When the toon is over, click on him to unlock a secret minigame: "Super Kingio Bros."

Also, in the toon "Halloween Potion-ma-jig" The Cheat is dressed as Toad.

In the toon "Teen Girl Squad Issue 10" the character Tompkins is apparently playing a Mario game on an old Game Boy. A Koopa shell "pÃ˜wn"s So and So.

The game "Stinkoman 20X6" features its very own version of the Minus World, Level -0, "NEGATORY". Unlike the Minus World, it is beatable (as well as part of the game), but is far glitchier than Minus World.