Within the game's data are unused icons depicting an orange version of Mario and an orange "S" emblem in the vein of the ones on Mario & Luigi's caps. While the rest of the game's data provides no clues regarding their purpose, the use of the letter "S" implies that they may have been intended for a version of the Super Guide function from New Super Mario Bros. Wii.

By coincidence, these unused graphics also resemble Sponge, a fan character conceptualized by and prominently featured in the content of Twitch livestreamer and YouTuber Vinny Vinesauce, who came up with the character during a playthrough of Super Mario 3D World in 2014. While the graphics predate the character's creation, they were not discovered and publicized until 2015. Vinny himself commented on the parallels in a YouTube video parodying the style of gaming trivia channel DidYouKnowGaming.

In a 1996 interview with Shigeru Miyamoto published in Super Mario 64's first Japanese strategy guides, he revealed that Mario's running animation, speed and movements in that game were influenced by Arale, the main protagonist of the 1980 Akira Toriyama manga/anime "Dr. Slump":


However, Dr. Slump's influence throughout the Mario series could trace back even further. Some particular examples from Mario games include:

• His running speed, animation, the Racoon and Tanooki Suits from Super Mario Bros. 3
• The Wing Cap from Super Mario 64
• The Cat Suit from Super Mario 3D World

Even traits of Mario's happy cartoonish personality, his short stature and gloves, and blue-red-overalls color scheme bear enough similarities that they all could have been taken from Arale's appearances and other elements throughout Dr. Slump. Despite this, outside of Miyamoto's comment, these connections are not known to have been elaborated on by any other employee from Nintendo.

Almost every object in the game freezes in place when you die. Plessie is the only exception to this rule.

An unused song, listed as "Mario3House02.sg.32.dspadpcm.bfstm" can be found in the game's data. It is unknown what or where the song could have been used.

The level Mount Must Dash is a reference to Super Mario Kart, with the music being a remix of the Mario Circuits' music.

According to the game's Producer, Koichi Hayashida, Peach was not originally intended to be playable at the start of development, and was intended to be the damsel in distress character as she is in other Mario titles. The idea of her being playable was brought up by the game's producer, Yoshiaki Koizumi, who told the team that Peach should be playable, stating "I think she adds a lot to the sense of competition when you get in multiplayer. You can have different people choosing different characters based on their personality or whoever they like. And Princess Peach is just really a lot of fun to play!"

The theme for the Captain Toad levels is the Toad Brigade theme from Super Mario Galaxy.

The end of the E3 2013 reveal trailer shows Mario making it to the top of a flagpole and being rewarded with 10,000 point as well as an extra life. In the final game, reaching the top of a flagpole only rewards the player with 10,000 points.

This was most likely changed because the player could use the Cat Suit to climb to the top of the flagpole, making it incredibly easy to get a 1-up every time they reach a flagpole.

The game uses the same death jingle as in Super Mario Bros. 3.

If Toad is at his smallest state, his head's color scheme changes from white with blue dots to blue with white dots.

The idea of the 'Clear Pipe' came from the game's producer, Koichi Hayashida, wondering "What's Mario up to while he's in there?" while travelling through the iconic green warp pipes of the series.

8-bit Luigi spites can be found in various places throughout the game.

After beating the game, a Luigi-themed Mario Bros. game called Luigi Bros. can be played by tapping a Luigi button in the bottom left corner of the title screen. This can also be played right away if save data for New Super Luigi U is detected.

Hidden halfway through the first level of World Star is a cloud which will launch the player to a secret bonus stage consisting of tiles floating in space. Lighting up the tiles will reveal Link as he appears in The Legend of Zelda, accompanied with a disco rendition of the series theme.

Director Kenta Motokura has said that the "Double Cherry" power-up was made after somebody on the development team made a mistake, accidentally placing two playable Mario characters into the same level.