good stuff you got going on
You've got a really good thing going on in terms of graphics and content. The designs of the characters are cool/cute and the color palette is really nice; your line work is pretty nifty looking too. The facial transitions were seamlessly done and looked cool, so good job there!
The movement of everything isn't bad, I just feel the timing of everything could use work. Of course, unless it was a stylistic choice, some of the movement felt weird: when the one boy was swinging the bat it came down so slow and unrealistically. Other places timing could be improved are when the skeleton grabs the boy. The two times the boy is tossed (once in the train and once through the door) are tweened and done so very slowly and its creates kind of an 'I rushed this' impression. But nothing so significant it distracts from the piece as a whole, so bravo!
I really liked the ending too, it was pretty funny. Anyway good job and hopefully you got something out of my criticisms/compliments. :)