Revealing mistake: As they recover the car from the canal and open the door to reveal the girls dead mother, you can see her still breathing as they lie her on her back to examine her.
Revealing mistake: When the CSI from Miami and Catherine are in the autopsy, the guy goes to take a sample from the eyes of the dead woman. When he moves the swab towards her eye, you can see the actress' top eyelid move instinctively. She's supposed to have been dead for hours.
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.