Plot hole: Mater tells McQueen he moved and looked like he just saw the Ghostlight. Sheriff gets on to Mater for talking about the Ghostlight and then their whole plan falls into place to trick and scare Mater with the blue lantern. Only there's no way they would have known that Mater would have mentioned the Ghostlight after that. McQueen didn't know about it, supposedly. And he had been scared by Mater and had been there enough that he would have known if Mater had mentioned it before, and Mater would have known he told McQueen.