There are these things in races the game calls "Race Gimmicks". Each gimmick has a different effect (see below). Also, your endurance does not automatically restore while in a race and when it reaches 0 you retire.
The above gives you a Speed Boost.
The above Restores Endurance.
The above gives you Buggy Points.
The above explodes when you touch it.
The above three items are obstacles.