Here is a video of all 'official' shortcuts in Mario Kart DS.
This means no out of bounds exploits or glitches which allow you to skip huge parts of the track, or obvious cutting of corners using mushrooms, stars or other items. Essentially, anything intentionally placed or hidden by the developer.
These are useful for beginners, and / or those looking to do no exploit multiplayer matches and time trial laps.
![](https://i.ytimg.com/vi/2YOaEf08NtA/maxresdefault.jpg)