An unused test course can be found stored in the game's memory. Its mini-map resembles the Peach Circuit track, and has no AI routes for CPU drivers. It uses the same background music that plays in Peach Circuit, Luigi Circuit, and Mario Circuit.
This is the first Mario Kart game to feature a Lighting Cup. It is also the only Lighting Cup with original stages, as from Mario Kart DS onward, it only featured stages from previous Mario Kart games.
Despite the Monty Moles from Donut Plains 2 and 3 being removed, the holes they pop out from were still updated with new graphics in the tracks' tileset.
Sky Garden is the only course in the Mario Kart series that appears in the same cup in two different games.
Triple Bananas, Golden Mushrooms, Fake Item Boxes and Bo-ombs were all going to return as items but were cut for uknown reasons. Their sprites can still be found in the game's data.
In the preview image to the track Sunset Wilds, the Shy Guys wear Native American headdresses in the Japanese release. These were removed in the International release.
Bowser's Castle from Paper Mario makes a small cameo in the Rainbow Road course.
There are Tilemaps and Minimaps for all of the battle courses from Super Mario Kart. While these might have only been used as placeholders before the new ones were completed, it may also have also been possible to unlock these courses just like the tracks at one point. These are all stored in one piece, unlike the rest of the tracks and battle courses, which are stored in chunks.