In PBR, there are several checkpoints throughout the map which keep the player from skipping large portions of the tracks. These must be driven over in order for a lap to count. For instance: in the mansion stage there is a skip you can do that WOULD save a good 10 seconds off of a lap time, however it also skips one of the checkpoints throughout the stage. When you pass over the finish line after doing this skip a lap is not counted and you must go all the way around until you hit the checkpoint. At the moment the only stage to abuse this system on is the first one. If you drive around the beginning corner of the stage and turn around at the right spot, you hit the only checkpoint in the stage (not counting the finish line) and are able to go back to the finish line and drive forward over it to count as a lap. Driving forward over the finish line is necessary in order to pass a lap.