Do the following achievements to enable the corresponding effect:
Cheat mode: complete championship mode without using any
Random Checkpoints option: complete championship mode
Speech Test option: complete championship mode
Cheat Sheet option: win the Rally Days 1 race without collecting any pick-ups
All skins: get the three hidden pick ups in the Valentine's Day race. (Two are at each tower, the last one is behind the Skater picture in the jungle.)