1876
In Mario & Luigi: Partners in Time, a glitch can be used to sell any item for the regular selling price of any other (potentially much more expensive) item, allowing immense amounts of profit to be made. Details in image.
1877
In The Legend of Zelda: Majora's Mask, the back of the Happy Mask Salesman's backpack is decorated with, among others, a Mario mask. Here is a comparison of the mask in the original Nintendo 64 version (left) and the 3DS remake (right).
1878
In Super Mario Odyssey, whenever Mario throws his cap, there is one frame between Cappy's eyes not being present on the cap and them being fully visible where the eyes are much smaller than usual.
1879
Concept art for Captain Toad: Treasure Tracker characters not present in the finished game, from the 2015 Nintendo company guide. Top: a living door that quizzes Captain Toad to proceed, bottom left: Goombas with accessories, bottom right: Cat Captain Toad.
1880
Top: official artwork of Mario's mustache without his nose, released by Nintendo of Japan for Super Mario Odyssey. We can see that while most of the mustache has a more realistic texture, the middle, normally covered up by the nose, has a different, more stylized texture.
1881
Unused low-polygon Goomba model from Super Mario 64 DS.
1882
In the data of Paper Mario, an unused sprite of Peach kissing someone, presumably Mario, can be found (left). As the sprite is only present in a palette used for dark areas, a mock-up of the sprite with the regular palette (and Mario for demonstration) is provided (right).
1883
Limited edition Japanese "Mario Silver" Nintendo 3DS XL, featuring an emblem of Mario and Luigi reading "We are twins! We are twins! Super Mario".
1884
In the microgame "How the West Was Really Won" in WarioWare: Smooth Moves, failing results in the cowboy's underwear being revealed, which features Super Mario World power-up sprites. In-game, this is partially obscured by the timer; here is the graphic extracted from the data.
1885
Artwork made in Mario Paint depicting a Yoshi-colored T. rex, from Nintendo Power's official guide for Mario Paint.
1886
Production photo taken during the filming of the North American commercial for Mario Party 4.
1887
Unlicensed New Super Mario Bros.-themed seat belt covers, featuring artwork of Luigi from Luigi's Mansion and the same artwork with Luigi wearing Mario's clothes, presumably intended to be Mario.
1888
Scene showing Shigeru Miyamoto's workstation at Nintendo of Japan decorated with a hanging Mario toy in 1993, seen in a French documentary about Japanese game companies.
1889
Unused model of Mario found in the files of Pikmin. The model is notable for giving Mario a brown-colored, rather than black, mustache and adding folds and creases to his clothes that are not present in this magnitude on even his most detailed models to date.
1890
If Mario is in the front when exiting the Starbeans Cafe in Mario & Luigi: Superstar Saga, Luigi will be drawn on top of Mario during the few frames the screen fades in, appearing to be standing on Mario's face. If Luigi is in the front, nothing happens.
1891
As is widely known, the international version of Super Mario Bros. 2 is a graphical edit of a Japanese-only game called Yume Kōjō: Doki Doki Panic. Almost all enemy artwork was left unchanged except for the Pokey: compare the American edit (left) to the Japanese original (right).
1892
BS Super Mario Collection is an enhanced port of Super Mario All-Stars for the Japan-exclusive Satellaview peripheral. In the Super Mario Bros. 3 section, the Toad Houses were redesigned from a playable screen into a dialogue window, using these unique Toad dialogue portraits.
1893
Illustrations of Candy Kong in her Donkey Kong Country TV show design beating up various Kremlings and King K. Rool, from a set of Japanese Donkey Kong trading cards.
1894
Paper Mario sticker from Metroid Prime 3: Corruption, unlocked as a decoration for Samus's Gunship by having the game detect a Wii save file for Super Paper Mario on the system.
1895
Unused early Bomp models from Super Mario Galaxy. In the data, these have a different name from Bomps - their name is "ツキダシくん", which translates to "Bomp-kun"; "kun" being a Japanese honorific used to address young males.
1896
Thanks to the efforts of Twitter user @reborn_cookies, the Yoshi statue from the previous Tweet has been identified as part of a GameCube exhibit at Nintendo of America in the early 2000s.
1897
Luigi greeting commuters in Chicago on August 12, 2013, when a Nintendo promotional event decorated the L train with Luigi imagery to celebrate the Year of Luigi.
1898
Sprites for an unused bird found in the data of Mario & Luigi: Bowser's Inside Story. Since the sprites are next to Broque Monsieur in the code, it is possible that these birds were intended to be collectible in an early version of the game, as Blitties are in the finished game.
1899
The cover of "Mario and the Incredible Rescue", a licensed Mario book, contains 5 pieces of artwork from 4 games: Mario and a 1-Up Mushroom from Super Mario 64, Luigi from Super Mario 64 DS, and two Boos from Mario Kart 64 and Luigi's Mansion, respectively.
1900
Concept art for Buoy Base Galaxy from the official Prima guide for Super Mario Galaxy.
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