The update is available to download through the eShop.
The update for Mario 3D Kart is now available to download through the eShop. The patch fixes exploits found within three different tracks that many users have been using to gain an unfair advantage in online multiplayer races.
The three courses which have been updated are Wuhu Island Loop, Wuhu Mountain Loop and GBA Bowser Castle 1. Players who choose not to download the update will not be able to participate in any online races. The patch does not affect time trials.
The update is live right now in all major regions.