Is there cheats to unlock courses on mariokart Wii?

not on all of the courses. on maple treeway after the start veer to the right and there is a shortcut that should put you in the lead if you have a good start. the begining part is a little slow but then there are some boosts and you will go right into the cannon. (veer to left in mirror mode) in koopa cape if you have a boost item you can go in between the big red shell on grass and you will pass people.