Contrary to popular belief, the Mushroom Kingdom stage in Super Smash Bros. does not use sprites or music from Super Mario Bros.. This can be seen in obvious ways, such as enemy sprites having complex shading that would be impossible in any NES game, let alone a title as early in the hardware's lifespan as Super Mario Bros., and multiple sprites being miscolored. It can also be seen in more subtle ways, such as the ground blocks being one pixel too tall on the bottom, and the outlines on the goal stair blocks being too thick. The background music, while an impressively close replica, uses subtly different instruments and is slightly slower in tempo.

In Super Smash Bros. Ultimate, the stage's graphics would be revised to more closely resemble Super Mario Bros., using graphics from Super Mario Maker, and the faux-8-bit Super Smash Bros. rendition of the overworld theme would be the sole battle song from that game to be absent, in favor of the original NES rendition of the song.