When Nolan and Juarez leave the station at the end, one of the SUVs is seen parked behind them with the license plate 9999960. This plate was also used in SWAT S6E6 on armored car Black Betty Rescue 1.
When Frank and Lucy are having dinner, a car with the license plate 2FAN321 pulls up and the passenger shoots up the restaurant. This plate was used in S5E4 on a miscellaneous SUV, and in Destroyer (2018) on a miscellaneous car that is parked at an intersection when Bell is tailing Petra to the bank heist.
Lucy's blue UC car has the license plate 3JRQ158. This plate is used later in this episode on a silver Honda Accord where Smitty and Thorsen find the dead liquor store robber in the trunk. It was also used in S5E7 on Dr. Mitchelssen's car and in The Rookie: Feds S1E3 on the FBI surveillance van.
When Lucy drives to her UC job site, a Toyota Camry on the very left of the screen has the license plate 2WAC484. This same car and plate shows up later on at the factory where Frank takes Lucy when he wants to kill his men. This plate was also used in S5E13 on a pickup truck that was being loaded with stolen goods.
When the drive-by shooters get out of their car to run, a truck with the license plate 2QCE265 is parked on the street. This plate showed up in S5E3 on a self-driving car, in S5E8 on a car belonging to collar-bomb victim Pam, and in SWAT S6E19 on a car used by Jamie Wilson to run down Eric Hoffman.