Mario Kart Crisis is the first bonus chapter in the comic. The main characters being Wario and Waluigi, and the main villian being Morton Koopa Sr.
Wario replaces Mario
Waluigi replaces Luigi
Morton Sr. replaces Bowser
Morton Jr. replaces Bowser Jr.
Mario Kart crisis starts by Waluigi running to Wario telling him that he wasn't in Mario kart 7, and he wanted to know why.
Wario: "let me see that case"
Wario finds a letter in the case saying:
"hey! Purple guy! Noticed you're not in this game! heh...that's my fault! If you ever want to be in a Mario Kart game again, or any game again, you got to beat me! The Grand King Koopa!