Revealing mistake: Season 5 Episode 18 "Spark of Life": when they show a closeup of the badly-burned woman during her debridement, it can be seen that even though her eyebrows and hair and, in fact, 90% of her skin has been burned away, she still has long, full eyelashes.
Factual error: Sanders is seen in the burn victim's OR, during debridement, wearing his street clothes (under a paper apron), and no mask or hat. Considering that the woman's skin is practically one continuous open wound, and her immune system is in an exceedingly fragile state, there's no way a breach of sterility like that would be allowed.
Other mistake: Episode 18 Season 5 "Spark of Life": Late in this episode, the CSI crew is sitting around discussing the case. Sarah Sidle summarizes the facts in the case, including making the comment that Tara Matthews was attacked by the truck driver "just before her death"; in actuality, while Tara was severely burned, she remained alive in the hospital throughout the entire episode.
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.