Luigi's Mansion was originally developed with the intention of being in 3D. All Nintendo GameCube systems support display of stereoscopic 3D. Nintendo decided to shift focus away from 3D at the time as a 3D screen add-on would have cost more than the Gamecube system itself. Stereoscopic 3D would later be used in the game's Nintendo 3DS remake.

Before going into the Training Room in the original game, a menu will appear giving the player different controller options. After waiting for a couple of minutes, the music track will change to a funky beat, 19 notes will play, and the original music will then return. These 19 notes are actually Totaka's Song, a song that is hidden in almost every game composer Kazumi Totaka has worked on. In the game's Nintendo 3DS remake, this control selection screen only appears during the first time you go to the Training Room, giving you only one chance on that save file to find this Easter egg.

The training room is completely modeled out in the 3DS version compared to the original release on the GameCube. However, in both cases, the player cannot use the Game Boy Horror, making it impossible to see through normal means.