Paper Mario was also originally going to be named Super Mario RPG 2, though due to complications involving Square Enix, the makers of Super Mario RPG: Legend of the Seven Stars, the name was changed to Super Mario Adventure and later Paper Mario.

In Boo Mansion, if the player goes through the door across the hall from the entrance and jump in the jar inside, Mario will come out of the jar looking like his original 8-bit sprite from Super Mario Bros.

Waiting an additional 10 seconds after the jingle that plays on chapter title cards will cause a complete version of the Super Mario Bros. theme song to start playing.

Luigi keeps his diary in a secret basement under his and Mario's house. If you manage to read the entries, you can find one entry reveals that Luigi is afraid of ghosts, and another where he says he wants to have the lead role in his own adventure. These diary entries are referencing Luigi's Mansion, which was in development at the time.

At the Toad Town train station, there is a blue Toad who tells Mario that after he defeats Bowser and restores peace to the Mushroom Kingdom, he has something else he wants to tell him. However, no such event can be triggered as it's impossible to access the train station after defeating Bowser, making the line pointless as you cannot talk to him again. It's possible that this was meant to be part of content found in the post-game, but was cut during development.