nice attempt
since its ur first flash, u gotta give evrything you got to make a good impression. an obvious inspiration should be "alvin-earthworm." u should study how he does things cuz his sprite animations are freakin epic. If you already kno him, than great.
Lots Of Work
Work a lil more
crude
On the tachnical side your characters are not really moving, most of the time they keep flickering from one location to another which lets them appear very unnatural. When they are crossing the bridge it really looks like it is: The characters are running on the spot while the background moves behind them with a tempo that doesn't match their steps. And try to remove the gap when the background repeats.
The bgm is mediocre and doesn't follow the action very well.
When the plot is 'over', the whole movie starts anew, over and over and over again... Maybe you should add an ending-screen.
Also the characters seem to have no good reason to be fighting in the first place.
not bad
im just not sure who is on what side.