Factual error: At the end when Ben Willis and his son have Julie at the graves, Ray shows up with a gun. He fires at Ben but there is no bullet in the chamber. Later after the fight between Ray and Ben's son Julie picks up the six-shot gun and fires 8 shots at Ben.
Factual error: Ray escapes from the hospital. The machine he was hooked to wouldn't go off like that causing panic. It would simply show "leads off".
Answer: I think that Estes already knew that Will was Ben's son. He had made a comment about a man (Ben) killing his wife (Sarah) in the same room Julie and Will was staying in. He also makes a comment about Will having his mother's eyes. So he probably recognized him. He also knew that the answer they gave to the radio host was wrong, and that proved it was a set up from the beginning.