The Finger - S2-E14
Continuity mistake: When Catherine goes into the diner with a man and Sarah is sitting talking to her date, in one shot they are talking and in the next immediate shot he has a cup to his lips.
The Finger - S2-E14
Visible crew/equipment: Nick goes into a house with a bird inside. As he enters the house, you can see a crew person (with a beard) in the reflection of the frame.
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.