Why are the trolleys in San Andreas repeated?

1. Before the task is triggered, CarlJohnson will receive a phone call, and the caller claims to know the Johnsons.

2. After that, there will be a task point marked with a question mark on the map, which is the task point of the Bigfoot.

There is a time limit for the task, because Carl must meet the requirements of the mystery man, that is, he must be ranked last, and his score must be within 6 minutes and 30 seconds before he can complete the task.