Revealing mistake: When Billy smashes through the door of Linnea Quigley's house it's obviously made of cardboard.
Revealing mistake: The sheets tying Billy's wrists to the bed aren't tight enough to keep him bound.
Revealing mistake: The robber who kills Billy's mother is shown cutting her throat but with the flat side of the blade. Moreover real blood doesn't ooze out so thickly, indicating it was makeup.