Nintendo DS (battle course)
Nintendo DS is a battle arena first seen in Mario Kart DS. Designed to look like the original Nintendo DS system, the arena is simply two connected platforms, with one, the "bottom screen" flat, and one, the "top screen" slanted. The "screens" are not known to change images. While Mario and his friends battled atop the course, the screens were decorated with a screenshot of Mario Kart DS's title screen. While not quite as curved as a real Nintendo DS, the arena is a very accurate representation, going so far as to include details such as the microphone.
The course is located in a starry region of Outer Space. While the arena does not appear to move around in space, it has no evident technology to keep it in a single place. It is likely that the same method used to suspend the Rainbow Roads and Nintendo GameCube arena is the same used to suspend the Nintendo DS.
The missions 1-5 and 7-6 take place on this course. In both missions, there are gates the player is supposed to drive through.
When a player plays Mario Kart DS on a Nintendo DS Lite, Mario's call on the title screen is different. The fact that the title screen is displayed on this course may be a sly reference to the easter egg.
This course is probably made to mirror Mario Kart: Double Dash!!'s Nintendo Game Cube track, however since it's now on a different, system, they change it to Nintendo DS.