ok, i dont dare to crit, cause i cant do 10% of what u have done. But, if you dont mind…
I think the top bomb or ball, whatever it is, that they are throwing, breaks the wall before it even touches the wall. I guess ur pivot for the force is in front… which makes it hit the wall before the ball actually hits it and thus break it.
Same goes for the second ball, the area it affects is a little “not practical”. I mean, its fine, but if u want to refine it, then… cause when it hits the wall, it first breaks the wall, then the wall seems to get back to itself, then falls apart… i mean, i know its supposed to happen like this, but just that the area seems a bit not right.
And, its just my personal thingy… i was expecting only one ball to hit, cause i saw one Trebuchet to shoot. But its fine… =p
in total, w/o any question u have raised the whole level of the competition. really nice. i had to go wow. 
I hope you dont mind my comments, and i hope i am wrong… cause its a really good work, and i dont want it to have flaws.