The Mosquito 100 Race is the first episode of Regular Show Adventures, plus the first appearance of Wally
The episode starts off with Mordecai and Rigby reading the newspaper. They are suprised when they see the main article is about the local Mosquito 100 Race coming to town on Thursday. They are ready to enter, but realize they have no car. Mordecai tries asking Benson to give him and Rigby his golf cart, but Benson says they can't go to Mosquito 100 Race because they have work to do on Thursday.
Thursday comes and Mordecai and Rigby try to find a way to get into the Mosquito 100 Race. They look inside the phonebook and at Category:W they find an ad for Wally's Workshop, a place where things can get built and fixed.
They head to Wally's Workshop and meet Wally the Worker, who is currently working on a Strasburg #90 steam engine. He meets Mordecai and Rigby, who come to his workshop for entering the Mosquito 100 Race. Wally agrees to help them win, but only if they'll agree to give him the tools he'll need to modify the cart. Mordecai gets the tools while Rigby stays with Wally and the golf cart. They get to work on Benson's golf cart while Wally's theme song "Hardware Store" by 'Weird Al' Yankovic plays on the boombox.
The trio enter the race just before tickets are sold out. They race all 99 laps to "Hardware Store" playing on the surround-sound amplifiers attached to the back of the cart. Benson discovers Mordecai, Rigby, Wally and his golf cart on TV at the Mosquito 100 Race. He races to Wally's workshop to find them, but does see a note from Wally that says: "Entered the Mosquito 100 Race with a blue jay and a brown raccoon. See you tomorrow! -Wally."
At the race, Mordecai, Rigby and Wally are down to the final lap and drift their way to first place. They win the 1st place trophy (which is shaped like '#1'), 1,0000000,0000000,0000000 dollars.
Next morning, Benson is really mad at Mordecai and Rigby. Wally tells him they wanted to win and wanted to keep the golf cart. Benson remembers that he has a spare golf cart and tells them he can keep it for eternity. Mordecai, Rigby and Wally reply by doing the 'OOOOOOOOOOOOOOHHHHHHHHHHHHHHH Song' until they walk inside the house.
- Muscle Man
- High-Five Ghost (does not speak)