Paper Mario: The Origami King
A group of Toads surrounding a cactus in the Scorching Sandpaper Desert say the lines "Morbid stuff, huh?", "Free at last!" and "I need closure." when pulled from the ground. These lines are a reference to the 2019 album Morbid Stuff by Canadian punk band PUP, including the songs "Morbid Stuff", "Free at Last" and "Closure".
The game's sudden announcement two months before release was due to Nintendo's struggles in transitioning to a work-from-home structure during the COVID-19 pandemic.
If you inspect the steering wheel of The Princess Peach cruise ship while Bobby the Bo-omb is next to Mario, he will remark how he once dreamed of being a captain or an admiral. This is a reference to Admiral Bobbery, Mario's Bo-omb partner from Paper Mario: The Thousand-Year Door