Very creative concept, too bad you had to rush it.

I know how you feel, I do that nearly every week.

Thanks for that skeddles.

Yeah, I started the whole thing a little bit late and ended up hurrying just to meet the deadline. Big mistake on my part.

Very good job, i like the concept. May I make a couple suggestions?

In all pieces, put more contrast between colors. This will make your piece pop out more, and it will greatly improve. Also, try to put them in more dynamic, or 'active' poses. He looks like he's hardly trying.  Maybe you would have him holding the wand with two hands, and legs widened. Also, The cheese blends in with whatever is in behind it(i'm guessing light from the mouse hole).
You could also add more sparks and stuff on the magic, it would bring the piece to life.

I wouldn't do it on this piece, for it is part of a contest thats deadline has been met, but consider these things on your next piece, and you will greatly improve. Before you submit your next piece, try give yourself these kinds of suggestions, and work on them. If theres something you just cant seem to get, visit the forum, or just PM another member(feel free to ask me anything) Keep up the good work.

That would be light coming in from the outside.

Mmmm It's hard to understand the scene, and what's that yellow triangle?
Also the piece lacks shading, use it to give depth to your drawings.