Boost From Starting Line:
A common move in all Mario Kart games is the ability to boost right from the starting line. This is done the same way in the GBA version of the game. To do it, you need to press the accelerator as soon as the green light comes on. You need perfect timing to do it, but if you do you'll boost ahead of the other racers right at the start.

New Title Screen:
To see the new title screen (which just features an orange background instead of blue), complete all the circuits in 50cc, 100cc, and 150cc.

Unlock Classic SNES Tracks in GP mode:



In order to unlock each classic cup you must first complete the entire circuit one time with at least a gold in each race. Then play through that each cup one more time and collect at least 100 coins and the Classic SNES version of that cup will then be unlocked.

Unlock Classic SNES Tracks in Time Trial:
Once you have unlocked the SNES tracks in 150cc you will then be able to play through them in the Time Trail mode.

Unlock Special Cup:
To unlock the final circuit, Special Cup (which includes Star Road), all you need to do is get a gold trophy in each of the earlier races.