When Billy goes through his little dance montage/fit there is a part when he's on the brick wall thing. While he's dancing you can clearly see that the wall faces the houses across the little street. Then he jumps from the wall STRAIGHT OUT, away from the house. But when he lands he is facing down the street, not the buildings across the way. In order to do that he would either have had to jump off at an angle (which he didn't) or twist about 90 degrees in midair (which I doubt he did). Oops...