Magma Moon Marathon shortcut:
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Begin the race and get to the point right after the
flaming objects shoot up in the air. Drive all the way
over to the right side to find a blue power-up.
Use this power-up and look at the strangely shaped,
flashing wall. Go through it to the other side. You
will end up at the clear dome. This shortcut can be
used only when the blue power-up is active.