Brian is an undercover cop. They "arrest" him in order to find out if he's gathered any useful information.

DOM: When you're not working at Harry's, you're working here. If you can't find the right tool in this garage, Mr. Arizona ... you don't belong near a car.
MIA: [to Brian] He owns you now.

JESSE: Dear heavenly ... spirit. Thank you for providing us with the direct port nitrous injection, four core intercoolers, ball bearing turbos, and titanium valve springs. Amen.
LETTY: Praying to the car gods, man.

Hector comes into the shop and orders "three of everything", tipping Brian off that another heist may be in the works.

Dom attacked the man responsible for his father's death with a 3/4 inch torque wrench.

DOM: He was comin' up in the pro stock car circuit. Last race of the season. Guy named Kenny Linder came up from the inside on the final turn. Clipped his bumper. Put him into the wall at 120.

He takes her out for Cuban food at Cha Cha Cha, a restaurant Vince had previously invited her to.

As Brian arrives, Jesse is about to race Tran for pink slips, despite Jesse's Volkswagen Jetta being severely outmatched by Tran's Honda S2000. Jesse engages his nitrous system prematurely. Thinking he has the lead he lets his guard down, and Johnny pulls past him for the win. Jesse panics and flees with the car.

He tells Mia that he's a cop and that Dominic and the team could be in trouble, hoping to convince her to help. Brian and Mia leave Race Wars in his Supra in pursuit of the team.

DOM: Listen, the other night l had a dream that you and l were on the beach in Mexico.
LETTY: Really?
DOM: Really. Come on. Let's make this happen.