Super Mario Bros. 3 is the first Platform Game to be able to scroll in every direction, including diagonally. Previous Platform Games were limited to straight up-and-down or straight left-to-right.
Author Phobia: Chain Chomps came from an experience Shigeru Miyamoto had as a child, when a dog chased after him as he approached but stopped just inches from him because the dog was tied to a stake.
Bad Export for You: Because the e-Reader flopped in America, half of the Super Mario Advance 4 cards never made it out of Japan, which left "World-e" incomplete with only one of the mini-game houses open and a rather empty e-Coin castle. All missing levels are available for the Wii U release of the remake, though.
Fan Nickname: Even though the DIC cartoon of this game has been dead for over two decades, many fans still use "Doomship" to describe not just the airship levels, but the ships present in Super Mario Galaxy and other future Mario games.
No Export for You: For the PAL release, SMA4 doesn't have the e-Reader features at all.
Serendipity Writes the Plot: The Boos' famous "shy when you're looking, mean when you're not" quirk was apparently based on the wife of one of the developers. Specifically, her frustration at him working long hours.
The dolphins that ended up in Super Mario World were originally planned for this game, but never implemented for whatever reason. This probably explains the abundance of "rising water" levels as well.
In addition to the extra World-e content in the Japanese version of Super Mario Advance 4, a lot more had seemingly been planned, as evidenced by the large amounts of unused content on the ROM and the fact that the world's castle, which displays the e-coins located in each of the World-e levels, was originally planned to have three floors, each with a full length e-coin gallery.