Continuity mistake: When Sara and Warrick are interviewing Meg at the end of the episode, the scene cuts between a medium shot of the dynamic duo, a close up of Meg's face and a close up of her hands which remain clasped on the table. The first time we cut to Meg there are tears in her eyes, but her face is dry. The second time we cut to Meg, there is a drying tear track on her right cheek. The third time we cut back to her, the tear track is gone, but there is a tear halfway down her left cheek. This continues throughout the scene.
Factual error: When Gris and Teri are looking at the bones that were found in the desert and discussing an electric saw, Teri is talking about the medial condyle of the femur but the bone they are looking at is the tibia (seen by the flatness of the tibial plateau - the femoral condyles are much more rounded, and the triangular shape of the shaft of the bone). It makes no difference to the story but having gone to the lengths to get the scaphoid and cuneform in the right place, it would have been nice not to get two major bones, that look completely different, mixed up.
Answer: He doesn't have the authority to arrest him - when anyone is arrested in the show, a police officer does it. Also he tells Ty that he is going to be submitting his case findings to Ty's insurance company, who would no doubt contact the IRS, who then would have him arrested for fraud etc.