Mario Kart DS
DK Pass: Mushrooms and stars in first place
Select the "DK Pass" level. Select any character and vehicle, but one that is suited for offroad driving is recommended. As you reach the top of the mountain, turn off the road and climb the steep snowy bank covered with trees. At the top of the hill is a single item block. No matter what place you are in, you should get either three mushrooms or a star. This also works in Wi-Fi mode.
Luigi Circuit GCN: Fly
Go to Time Trials and choose Luigi Circuit GCN. Do
a U-turn and face the middle of the arrow line. Try facing left
slightly. Yse a mushroom and jump when you are about to tilt.
If done correctly you will fly through the invisible wall then
fall through the grass. You will land back on the course. Note:
This will not save time.
Rainbow Road: Upside down stage
Go to the time trials and choose any character and car. Select Rainbow Road for the stage. When you get to the part that is only boosts, crash into a wall and jump. It will appear as if the stage has flipped upside down. Note: If you jump on the first area filled with solely boosts, sometimes you will just fly off into space and the stage will not flip temporarily.
Rainbow Road: Flipping and flying through the rainbows
To do this trick, tap the "Time Trials" icon at the menu screen. Select any character using any type of cart. Go to the track named "Rainbow Road". Drive up to the twisty track that is inside the swirly road. Just before you reach that twist, lightly hit the right wall of the twist and stop the kart. If you hit the left wall instead, you will fly onto the swirl and start over. You might also fly to the beginning of the twist when you flip and have to start over. You should still be moving slowly if you are in the correct position. When you reach about the middle of the twist, you should start rising off the ground as if in zero gravity. The first few times you might miss the track and float off into space, but keep trying. A few attempts may be required. If done correctly, you will fly through the ground, flip the kart, and start driving at the end of the twisty road and keep going. This all happens in about a second or two.
Waligi's Pinball: Fly
Go to Time Trials and choose Waligi's Pinball. Wait at the flippers for a ball to appear. Note: Use the touchscreen to see. When it arrives, jump in front of it. If it knocks you into the activated flipper, you may go flying. You can tilt your car forward and backward. If you land next to the wall but are on the outside, you can ride on nothing for a short while. However
if you go too far, you will die.
Steal two balloons
When playing against another person, if both of you have a mushroom ram into each other. If done correctly, you should have stolen each other's balloons instead of getting your own
back. Note: You can consider this a "trade".
Press A + B while racing to fly. This
glitch may cause you to reset, but may also be an easy way to
Go to any course in Time Trial mode. Turn your kart
so it is facing backwards. You will have the Lakitu following
you with the "Turn around" sign. However, if you are
using B to go backwards, the game will count it as one
lap, two laps, etc., but Lakitu will be saying you are going backwards.
When you are in a Balloon Battle with someone else
(preferably downloaded play), if both of you have a mushroom and
they are used at the same time, you both will steal each other's
balloons. Note: You will not get the balloon back that the other
Strategy guides from GameFAQs