How do I wake up the rat?

Hint 1 of 12:

The rat loves to eat carrots.  Maybe the smell of one would wake him.

Hint 2 of 12:

There's a carrot on the top of the screen.  You're going to have to shake it
loose.

Hint 3 of 12:

The cannon, if aimed properly, will do the job for you.  One important
thing to remember is that you can't load the cannon until it's pointed up.

Hint 4 of 12:

There's a stack of cannonballs at the bottom of the screen.  Find a way
to get one of the balls loose.