Luigi

Luigi is one of the many characters from the Super Mario series, being the cowardly brother to the heroic Mario. He often fills the roll of player two in most of his appearances, and is infamously portrayed as living in his brother's shadow.

Despite Luigi appearing in almost every mainline Mario game beforehand, Super Mario 64 is the first game to not show any signs of Luigi. While Luigi was originally intended to be in Super Mario 64 alongside its multiplayer mode, he was removed when the mode proved too troublesome for the developers. Despite this, Luigi's influence has seeped into some of the copies of Super Mario 64.

Eternal Star Statue
In the castle courtyard is a fountain with a large star statue in the middle. The star statue has a plaque underneath it, which has vague writing underneath it. While the most accepted reading is "Eternal Star Statue", some have read it out to read "L is Real 2401".

Unused Multiplayer Functionality
There are multiple remnants of the scrapped two-player functionality within Super Mario 64. This includes duplicates or empty pointers proceeding directly after Mario's pointers, and an unused camera intended to keep focus on two active objects.