One later appeared in Spaghetti Law where SMG4 put it in Mario's spaghetti as a prank, but accidentally poisons the Castle Inspector who then goes all crazy before passing out and ends up banning all the spaghetti from the Mushroom Kingdom.
A Poison Mushroom being sold by a black guy also appears in 99.5% Crazy making Mario go all crazy.
In Yoshrooms, Mario tries to feed Yoshi a Poison Mushroom as an attempt to kill him, but Luigi tricks him to eat it as well ("Wow, what flavor is it?"). Then Mario and Yoshi go on a crazy high adventure and become BFFs.
And in Ssenmodnar 2 (100th video), Toad eats one, becoming crazy.
- The Mushroom in Mini Italians must've been a special kind because when the plumbers ate it they shrunk, but when the Castle Inspector ate it, he didn't shrink; he passed away instead.
- A Poison Mushroom appears in Smg4's wallpaper posted on his facebook page, however it's not the weird inverted colored one from Mini Italians.