The California Highway Patrol strongly supported the program 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 Matthews' call sign - 21-50 - was the actual unit number of then-CHP Commissioner Bernard Caldwell. In mid-1956 the CHP dropped its support of the program over differences in story lines 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".
The production company (ZIV Television Programs, Inc.) made a determined effort to avoid any perception that children or minors were being exploited. The official ZIV writer's guide for "Highway Patrol" specifically stated that juvenile delinquents were forbidden and that it had to be obvious that any delinquent was an adult. The guide also stated that the show did not do kidnapping stories unless the person kidnapped was obviously an adult.
At the end of the show each week, Broderick Crawford would make a safety announcement. One of his famous ones was "Leave your blood at the Red Cross, not on the highway". He always ended by saying "This is Broderick Crawford saying see you next week".
Broderick Crawford played himself CHiPs: Hustle (1977), being pulled over for running a stop sign and explaining to Officer Jon Baker "You know, I was making those Highway Patrol shows long before you were born". (Baker responded with, "Yeah, they don't make TV programs like that anymore.")
The series' opening credits originally expressed appreciation to Bernard R. Caldwell (the head of the California Highway Patrol during the mid-1950s) for technical advice and assistance, much of which was provided on-site by CHP Officer Frank Runyon. After the initial seasons, Mr. Runyon continued to serve as a technical advisor but the CHP reduced its official support for the program. The opening expression of gratitude thus became more "generic". It read: "This program is dedicated to the Highway Patrols throughout the nation and their contribution to the safeguarding of public welfare. We are deeply grateful for the technical advice and assistance which made the authentic production of this program possible."
Although not given specific screen credit, the California Highway Patrol was pleased to give technical advice on the production, even as far as providing all the patrol vehicles used in the series, and uniforms, too (modified to remove all references to California).
While it was generally thought the program depicted the California Highway Patrol due to the technical assistance from the CHP and locations filmed in California, on several occasions this was disproved. In Highway Patrol: Stolen Car Ring (1956), Matthews says he is from California and just passing through. In Highway Patrol: Hitchhiker (1959), the robber from New York that had left a 1,400 mile long trail of robberies tells his wife it is a long way to California. Since it was shown in Highway Patrol: Mexican Chase (1959) and Highway Patrol: Illegal Entry (1959) that the state bordered Mexico, this leaves as the only possibilities Texas, New Mexico, and Arizona. These states can likewise be eliminated. New Mexico uses a state police agency, not a highway patrol. Arizona can be eliminated due to their highway patrol cars of that era being all-white. Texas can be eliminated due to highway patrol officers there not wearing the type of hats shown.
Dan Mathews also used the expression, "21-50, bye," at end of transmissions on the radio. Also, he often had to turn his car around in a rapid u-turn to proceed to the scene of the incident. Last, his son had the original patrol car a few years back, and maybe still has it.