Earth

Earth (or sometimes referred to as the Real World*) is a large planet that has made numerous appearances in the Mario series. Although its based on the real Earth it differs in many ways, such as it being more satirical and comedic and its inclusion of Warp Pipes, Fire Flowers and a few Mushroom World enemies.

Super Mario Bros. (cartoons)
In The Super Mario Bros. Super Show!, The Adventures of Super Mario Bros. 3 and the Super Mario World cartoon, Mario and Luigi are portrayed as having lived in Brooklyn prior to coming to the Mushroom Kingdom, where they were the owners of the Mario Brothers Plumbing service. One day while unclogging a shower they accidentally got sucked into its drain and somehow ended up in the Mushroom Kingdom via Warp Pipe. From then on the planet Earth made numerous appearances throughout the series such as in: Reptiles in the Rose Garden, Toddler Terrors of Time Travel, Dadzilla, Kootie Pie Rocks, Recycled Koopa, 7 Continents for 7 Koopas, The Venice Menace, Super Koopa and Rock TV.

Mario is Missing!
In Mario is Missing!, Mario is abducted by Bowser and is taken to the real world, where Bowser plans to melt Antarctica and flood the entire planet. Luigi must travel through the world's continents and save them from the Koopa Troops evil plan and at the same time save Mario before it's too late.