In Super Mario World, Mario's punching animation when he is climbing on the backside of a fence suffers from a discoloration in his arm, whereby part of it is pink.
Top: this can be seen most easily as Fire Mario, since the pinkness of the arm does not change even when Mario's shirt changes colors to white. The footage uses a glitch whereby a well-timed jump off a rotating panel can cause Mario to climb while mostly unobscured, showing the pink arm more clearly.
Bottom: this is an oversight resulting from how the game stores sprites. Each sprite is made out of 8x8 pixel squares (which are called "sprites" on the hardware level, not to be confused with the colloquial term "sprite" meaning the full image of a character) whereby each is assigned a palette. The two squares on the right, containing Mario's arm, are accidentally assigned a different palette (also visible by the outlines becoming black instead of remaining brown).
Source: MrPyt1001, Kaizoman, Mister Man
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