At the end of 2009 I was tasked by the (now defunct) agency I was working for to create some artwork with Mario characters. Nintendo was a customer for which we did advertising online for every game, so proposing something different seemed a viable thing to do.
I don’t know if the project ever got greenlighted by Nintendo, we were kept in the dark as much as possible by management. (my guess is NO)
Anyway I did a great deal of artwork involving the characters in everyday life often in real-world settings (Peach acting cool, Mario playing at the arcade, Mario and Peach at sea) before being moved on some other more urgent project. I never asked, they never told, and eventually all the art ended in backup drive, forgotten for years…
In Super Mario Sunshine, if Mario is hit by the flying enemies on Pinna Park Beach, his hat will be stolen and he will slowly lose health. This effect persists even in dialogue scenes, which makes it possible for Mario to run out of health while in the middle of a conversation with another character. Mario will perform his death animation, and lose a life once the other character finishes talking.
A localization oddity in Paper Mario: Color Splash: the washing machine on Vortex Island in the North American version is top-loading (top picture) while it is changed to a front-loading one in the European version (bottom picture). In order to justify the vortex still pointing upwards, the front-loading washing machine needed to be propped up against something. So the localization team decided to redesign the laundry room into a cave in order to include a rock for the washing machine to lean onto.