What you're seeing on their feet is motion blur. Try a faster shutter speed.
In my opinion, the selective coloring is really cheesy. It looks like you tried to spiff up a not so good b&w conversion by throwing in a "pop" of color. The crop is a bit tight as well, there's no room at the top of the boy's head. I'm also not sure where they are or why. The black and red make me thing Disney but it looks like maybe they're on a track. They're holding hands so they aren't racing...