The California Highway Patrol strongly supported this show in its first two seasons, and the production company was able to rent actual CHP squad cars. Generic "Highway Patrol" logos were placed over the real CHP emblems and studio license plates were taped over the genuine "E" (exempt) plates. The 1955 Buick Century two-door sedans seen were built especially for the CHP and were never offered for sale to the public. Two-door sedans were adequate, because the real CHP rarely arrested anyone at that time, being involved more with accident investigations, enforcement, and auto thefts. Major police powers were not invested in the CHP until 1964. The show's uniforms were copies of the khakis worn by the CHP including the state seal and the slogan "Eureka", except that the word "California" was removed. Authenticity was a major goal, and Dan Mathews' call sign, "21-50", was the actual unit number of then-CHP Commissioner Bernard Caldwell. In mid 1956, the CHP dropped its support of this show over differences in storylines and presentation, and refused to supply any more squad cars. The producers quickly acquired an incorrect Buick Super four-door hardtop to complete that season. Accurate squad replicas were ordered for the 1957 season, but the 1958 season cars differed from reality. The trailer hitches seen on the squad cars were for towing the film company's equipment trailers to shooting locations. Brand names of suspect vehicles were never scripted. They were always described as "a green coupe", "a tan station wagon", or "a dark blue sedan".
Chief Dan Mathews:
Although well known for his line via radio of "21-50 to headquarters", Broderick Crawford throughout the series failed to properly use the radio microphone. On occasion, he held it backwards and spoke into the metal clip that held it on the dashboard, and he usually did not release the push-to-talk button after speaking (this would have prevented him from hearing headquarters). Other actors such as William Boyett did not make this error when using the microphone.
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