The stations where Matthews was seen working were rarely identified. This time, when he calls in the Arizona tag, he calls to the Menlo station. There is a city in California called Menlo Park outside of San Francisco, but it did not have a highway patrol station.
Matthews comments that the license plates on the convertible are from out of state, and when he calls it in he says it is an Arizona plate. During the series' run the state it is set in is never mentioned, but some conclusions can be drawn from paying attention to the dialog in specific episodes. In this case, the state it occurs in is not Arizona, since it has already been named an "outside" state. All evidence points to the state being California, as in several episodes (such as this one) the setting is in the desert and in others the setting is near or at the Mexican border. Since Arizona has been eliminated as a location, the only other "desert" states are Utah --which does not border Mexico--and New Mexico, which is mostly desert and does border Mexico but does not have the forests, mountains, beaches and rolling hills seen in other episodes. California does.
Matthews' and Hanks' patrol cars are 1955 Buick Centurys.
Doc Taylor is driving a dark colored 1941 Oldsmobile Model 66 Coupe. The Oldsmobile emblem has been removed from the trunk lid. This vehicle was used as a stolen vehicle in Episode 1 and driven by (S) Ralph Neal.
Charlie Barrett is driving a 1955 Chrysler New Yorker Deluxe Convertible Coupe that belonged to the deceased suspect/son Walker/Wilkins. The Ford Panel Truck is a 1955 Model.