Continuity mistake: In episode 8-1 Dead Doll: When Warick finds the zip-tie in the trunk it is not looped, when he holds it up for Grissom it is looped. He would not have looped it himself.
You Kill Me - S8-E8
Continuity mistake: In Episode 8-08, "You Kill Me," when Archie takes the first kilo of cocaine out of the case, he takes the bottom-most left-most kilo. When he takes out the second kilo, he removes the same package with the empty space being two to the left of the one he would have removed.
Continuity mistake: In the Season 8 episode "Goodbye & Good Luck," near the beginning, Sara and Warrick bump into each other and Warrick drops his medicine. During their conversation, Warrick squeezes Sara's shoulder and then drops his hand. The shot instantly cuts to a view from behind Sara and Warrick's hand is back on her shoulder with no time (or reason) for him to have put it back.
Grissom's Divine Comedy - S8-E12
Continuity mistake: When Warrick demands to see the hands of a suspect, the suspect refuses and Warrick pushes him up against a wall. During which time, there are multiple angles which show Warrick wearing sunglasses, then suddenly not wearing them anymore. (00:23:30)
Continuity mistake: After Natalie lowers the car onto Sara Sidle we know her right arm is pinned and she cannot move it. When Sara hears the coyotes she starts to look around and see where they are coming from. At one point we can see Sara with her right arm inside the crashed vehicle. (00:22:25)
Go to Hell - S8-E3
Continuity mistake: After Amy is thrown from the balcony and dies, her eyes are open in one shot and more closed in the next shot after the camera cuts away to a shot of Catherine Willows. (00:41:00)
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.