Baby Crash costume - Collect all the Die-O-Ramas to unlock the Baby Crash costume.
Easy coins - Drink a Whumpa Whip and let a Ninja Penguin attack you. Then, pick up your coins.
Evil Crash costume - Find Cortex on Mystery Island, and behind him should be an owl-shaped lamp. Use the body-slam switch to raise the lamp, then enter the revealed cave and go to the right. Talk to the drone at the top of the small island to get the Evil Crash costume for 2,000 Coins.
Play as Crunch Bandicoot - Give Crunch Bandicoot 2,500 Coins at Midway to unlock him.
Play as N. Gin - Give N. Gin the Green Plutonium at Midway to unlock him.
Play as Nina Cortex - Giver Nina Cortex the keys at Midway to unlock her.
Play as Pasadena Opossum - Give Pasadena Opossum one Power Crystal at Midway to unlock him.
Play as Von Clutch - Give Von Clutch one Power Crystal at Midway to unlock him.
Second tier kart weapons - Spend 500 coins at Midway to buy the following character's second tier kart weapon from them: Coco, Crash, Crunch, N. Cortex, N. Gin, Nina, Pasadena, and Von Clutch.
Skeleton Crash costume - Talk to the Astro Land worker near the stunt arena to get the Skeleton Crash costume for 4,000 Coins.
Third tier kart weapons - Spend one Power Crystal at Midway to buy the following character's third tier kart weapon from them: Coco, Crash, Crunch, N. Cortex, N. Gin, Nina, Pasadena, and Von Clutch.