Infinity Train: Blossoming Trail: One of the guests who entered the Library of Flying Books Car is a human version of Olivia who is holding a living bomb in her hands in her portrait, referencing Bobby. Author notes even reveal that Lexi's origami abilities were inspired from the author listening to the OST of Origami King.
As promised by its official page, BoxxyQuest: The Gathering Storm is filled with nods to the Paper Mario series, particularly The Thousand Year Door. Most notably, the Hype Train’s layout is virtually identical to that of the Excess Express, and they’re both ridden in their respective games’ Chapter Six.
If you stand in a certain spot in the Battle Arena at night, you can see Mario and Vivian in the crowd.
In her Early-Bird Cameo in Chapter 3, Tyalie can be seen wearing a Princess Peach cosplay.
The "Sacred Seeds" sidequest is an obvious parallel to gathering the Bub-ulb seeds in Paper Mario 64, right down to a doorway appearing in the garden once all the seeds are planted. The quest-giver’s name, Mint Leaf, is even similar to Minh T., the Toad who helps you in Paper Mario.
Superstar Saga: Woohoo Hooniversity has ? blocks from earlier Mario games, including one from Paper Mario.
Paper Jam: This game is a crossover between the Mario & Luigi and Paper Mario series.
Super Mario Maker: A Paper Jam-themed event level was released in December 2015 to celebrate the game's release in Japan, and beating it unlocks a "Mario Trio" Mystery Mushroom costume.
Mario Kart: Super Circuit: Bowser's Castle from the N64 game is floating in the background of the Rainbow Road track.
Mario Party 5: The Star Spirits are the hosts of this game.
Super Mario 64 DS: The design of Goomboss is based heavily on the Goomba King from the N64 game. He later appeared as a Mission Mode boss in Mario Kart DS.
The Owl House: In "Thanks to Them", Amity is briefly shown wearing a red-and-white striped hat like Vivan's, referencing her being written as an LGBT character in the Japanese version of Paper Mario: The Thousand-Year Door.
