When you start on Maple Treeway (Star Cup),on the right there is a shortcut. After the count, stay to your right. When the gate stops, go in. The grass will slow you down, but there is a turbo and an item block. When you get the block, you'll be in a bad place. But the turbo gets you in a good place. So you would get a star power or bullet bill, etc. This takes you to the cannon.