The icon used in the Download Play app when downloading data for the game is a cruder, early version of the icon used for the final game. For unknown reasons, this discrepancy was fixed only in the Chinese release of the game.
A portion of the Bowser's Castle theme is remixed from Mario Kart: Double Dash!!'s Bowser's Castle theme.
Inside the game's files is an unused soccer ball. It's likely this could've been used for testing the models, or it could've been used for one of the Wuhu Island stages.
The retro courses from Mario Kart DS have been widened in this game while retro courses from the other games have all been shortened.
The results theme is a remixed version of the theme from Mario Kart 64.
On the Piranha Plant Pipeway track, the clouds are recolored bushes. This is a nod to the original Super Mario Bros. where the bushes and clouds are the same art with different palettes.
The game's initial lineup of playable characters, prior to unlocking more, are the original 8 playable characters from Super Mario Kart on the SNES.
In the European version of the game the track called "Music Park" in the American and Japanese version is called "Melody Motorway". Despite the name change, the American/Japanese name "Music Park" can still be seen on banners in the level in the European version.
On the track "Roselina's Ice World", the Comet Observatory and the starting planet from the Gateway Galaxy from Super Mario Galaxy can be seen in the background.
On March 15th 2012, Nintendo released a patch that stopped a glitch which let you skip a large portion of Wuhu Loop. This patch only covers the Online Multiplayer and not the Time Trials.