Flags measure your progress throughout Career Mode. A Career Race can have up to 3 Flags. Those Flags are earned by completing conditions (finish 1st, perform 2 360s, drift 200 meters, etc.) that are specified at the pre-race screen, which is at the beginning of the Race, as well as in the pause menus. Some Races grant a Race Reward, which is earned by obtaining all the Flags in that Race.