1976
Ending screen from Donkey Kong Land. This appears for less than two seconds after King K. Rool's defeat animation, and is immediately followed by the staff roll. Then, the game resets.
1977
NBA Street V3 for the GameCube allows the player to start a match between two completely identical teams of Mario characters without using alternate palettes or other visual indicators to distinguish them, possibly resulting in confusion.
1978
Jimmy T.'s "smug" expression, seen only once in the entire WarioWare series for a few frames during the credits to WarioWare, Inc.: Mega Party Games.
1979
In Super Mario RPG, Bowser's head will disappear under specific circumstances during the battle against Yaridovich. If Bowser is the 2nd party member and Yaridovich's upper clone attacks the 3rd, Bowser's head will disintegrate and remain absent for the duration of the attack.
1980
Mario Party contains a special message from Toad when a player collects 99 Stars in one game. There are currently no reports of any player achieving this without cheating or modifying the game.
1981
Japanese toy of Winnie the Pooh dressed in an outfit strongly resembling Wario's. While it appears to be a licensed Disney product, the packaging indicates no Nintendo license, meaning that the Wario reference is unauthorized.
1982
Cartridge artwork for the Brazilian version of Mario Bros. for the Atari 2600. Since the game's low-resolution sprites made Mario and Luigi's mustaches resemble mouths, it is possible the artist interpreted them as such and drew the brothers as children.
1983
Cafe Mario, an exclusive Mario-themed restaurant at the Nintendo of America headquarters in Redmond, Washington, is currently under investigation regarding cases of E. coli poisoning. Insider sources state that concerns about food quality at Cafe Mario have been raised for years.
1984
Extremely rare fully unobscured Wizard Toad artwork from Mario Party 2. Even though Wizard Toad is present in every regional version of the game's box art, he is always partially covered by other characters.
1985
Official Aquabeads designs of Mario, Luigi, Peach and Bowser from a licensed Mario Aquabeads kit.
1986
Nintendo addressing the controversy surrounding hand blistering from playing Mario Party in a public service announcement in Nintendo Power, offering free gloves to affected Mario Party players.
1987
Despite containing both a Princess Peach and a Princess Daisy piece, the licensed Super Mario Chess set does not designate either of them as a Queen piece, making them both Bishops. Instead, Luigi is chosen to be the Queen piece.
1988
Watt's burned sprite in Paper Mario. This is the only time Watt is seen without the spiky aura of electricity and may be the true shape of Watt's body.
1989
Joke from the packaging of a 1990 McDonald’s Super Mario Bros. 3 Happy Meal.
1990
A picture of Mario and Luigi's parents, as seen in a Yoshi's Island manga.
1991
Super Mario Bros. Deluxe contains a calendar spanning AD 1 to AD 3000, yet by using a system called the "proleptic Gregorian calendar", all dates prior to October 15, 1582 have retroactively been assigned different days of the week, making it inaccurate for historical purposes.
1992
Official art of Mario used to advertise a Nintendo game development seminar in Japan. Why Mario looks uncertain or uncomfortable is not explained.
1993
A prerelease screenshot of Paper Mario shows a beta Yoshi design (with the design from the finished game inserted for comparison). The beta design's arms are extremely short; had it made it into the finished game, it would have been the shortest-armed Yoshi sprite to date.
1994
In Mario Party 7, several polygons in Birdo's eyes are missing, creating holes that can be seen through. This is the only time in the Mario Party series that a character's model is incomplete in this manner. In total, 10 polygons are missing, resulting in 4 distinct holes.
1995
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.
1996
Unused "Yoshi Nozzle" found in the data of Super Mario Sunshine. It replaced FLUDD's head with a Yoshi head and would have presumably had some sort of licking functionality.
1997
By popular demand, here is a detailed explanation of the situation behind the deleted Ashley Tweet, which includes both the original Tweet and a modified version that complies with this account's veracity policy. I apologize once again to all my readers.
1998
Princess Peach reading a story to the Koopalings, from the comic booklet enclosed with Nintendo: White Knuckle Scorin', a 1991 music album released by Nintendo.
1999
Top row: screenshots of the levels Vulture Culture from Donkey Kong Country and Konveyor Rope Klash from Donkey Kong Country 3. Bottom row: the same levels with all foreground layers removed. The background has been recolored and reused in Donkey Kong Country 3.
2000
The 1988 Official Nintendo Sticker Album contains this artwork of Princess Peach with a unique mauve hair coloration, as well as a white ear.
Additional obscure Mario content for suppermariobroth.com.
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