All cars - Hit 11 Bonus Stunt items while completing Challenge 8 to unlock all cars.
All items - Intentionally hit at least 30 Barrels while completing Challenge 7 to unlock all items.
All worlds - Find the Hidden Key while completing Challenge 18 to unlock all worlds.
Infinite ammunition - Intentionally hit at least 50 Barrels while completing Challenge 18 to unlock infinite ammunition.
Infinite health - Intentionally hit at least 179 Barrels while completing Challenge 17 to unlock infinite health.
Infinite turbo - Collect 8 Zappers while completing Challenge 4 to unlock infinite turbo.
Timer speed - Intentionally hit at least 60 Barrels while completing Challenge 12 to unlock timer speed.
Upgraded laser - Successfully complete Challenge 18 on the very hard difficulty setting to unlock upgraded laser.