After you have completed the game, a "Weekly Challenges" button will appear at the top-right of the World Circuits pavilion screen.

As the name suggests, Weekly Challenges are race events that are available on a weekly basis. Complete challenges to earn rewards.

Select the button to see a list of available events and the rewards for completing them. These will mostly take place within World Circuits pavilion, although some races will be online-only.

Strive to complete all the events while they are available.