Super Mario Bros 3 is a very famous game for the NES. There are normally two main ways to beat it: the quick way using warp whistles to skip worlds (http://tasvideos.org/1590M.html) , and the longer way which goes through all the worlds (http://tasvideos.org/1558M.html) . However, thanks to some esoteric memory corruption involving glitched pipe travel, it's possible to jump right into the princess's room in under three minutes! Bowser is never seen in this run at all.
This run gets to World 7-1 as quickly as possible to perform the glitch, and some unusual moves are done with enemy spawns and positions to get the glitch to work. See the authors' comments (http://tasvideos.org/4288S.html) for some more details.
There are also author subtitles provided with the emulator movie file and primary encode to explain some of the key differences in this run.