I discussed with Steven on IRC about this issue.
His textures were drawn in C2's image editor.
When you preview the project in either chrome or FF, the collisions polygons seem off.
To fix it, go edit the "Player" sprite and either "set to bounding box" or "guess polygon shape".
Then the collision polygon of the Sprite2 seems to be finaly "processed" (before it looked like bounding box).
Could it be a bug somewhere ?