Speedflip
A speedflip is a glitch that allows the player to gain an arbitrary amount of speed. In the direction perpendicular to a sideflip, Mario's speed is not capped[1], meaning one can, under the right conditions, build up infinite speed in this direction.[2] Mario's acceleration in this direction is proportional to the component of the left joystick pointing in that direction, with a maximum acceleration of 0.075 units/frame2.
Speedflips currently have little use, but some proposed applications include finding a new infinite fall, and, combined with nut sliding, a new way to collect the Third Courtyard Outskirts moon in Bowser's Kingdom without capturing anything.[3] A speedflip has also been used to jump from the painting island in Bowser's Kingdom to the Third Courtyard Rear island.[4]
Mario's speed in the direction of the sideflip and his speed perpendicular to the sideflip are completely independent. This makes it possible to vector a speedflip, squeezing out just slightly more speed (though the acceleration is unaffected).