This is a clever concept, and the story made me laugh. I would suggest having Capt. Bullit move a bit faster. It was nigh impossible to walk to the gun and use it while having the plane going in the direction you want it to. I suppose that's what the crates are there to help with, but they just kept falling off the plane for me lol.
So yeah, with a bit more polish, this has really great potential! Keep up the good work!