Alvin, it sucks they rejected you, but your attitude tells me it would not stop you at all, on the contrary :)
What Mr. Mullen said is more important than it migh appear: your approach was comedic, therefore you may have thought a bit more about how to make each shot, each piece of puzzle more funnier, fresher, cutter, more suprising, like in his suggestions.
I also think you were lucky for not having $$ to crash the BMW and "wake up" from a dream. IMHO it would have been a cliché, such an ending, too easy way out of the story.
But you did achieve what good storytelling must do - your short engaged me, made me want to know what's going to happen next and, even, made me guess what would happen.
Good luck with all that you do!