In an interview with Satoru Iwata and Shigeru Miyamoto, it was revealed that an early, experimental build of the game had split-screen multiplayer, with Mario and Luigi as playable characters.

The game's planned multiplayer mode ended up being reworked into a Mario Bros.-style minigame thanks to the Nintendo 64's technical limitations making the split-screen concept unfeasible. However, in February of 1996 (just a month before E3 of that year), both multiplayer mode and Luigi were removed, in part because the Nintendo 64 was bundled with only one controller. These statements are corroborated by findings from the Gigaleak, a massive content leak of internal data from Nintendo in 2020 that included early assets from Super Mario 64. Among the leaked material was a model and textures for Luigi and sprites for "1P" and "2P" icons. Luigi's model is dated June 20, 1995, while the icons use the same generic font seen in the Shoshinkai demo from November of that year, rather than the custom font seen in both the E3 1996 demo and the final release.