To unlock cheat mode, go to the "Options" menu at Anthony's house and select "???". Select the lights in the correct order. Activate the following cheats by entering the corresponding codes:
CHEAT FUNCTION - CHEAT CODE Mirror mode - [Right Arrow] [Left Arrow] [Left Arrow] [Right Arrow], then Ladybug, Clover, Boy Face, Plane, Bus, Bike. Then, while selecting a stage in Free mode, press 2 to play the mirrored version. Master Higgins Ball - [Right Arrow] [Left Arrow] [Left Arrow] [Right Arrow], then Square Robot Face, Car, Award Ribbon, Bike, Helicopter, Strawberry.