In his E! True Hollywood Story (1996) bio, Lee Majors said he started his acting career by hanging out with stuntmen, and occasionally working as one. Majors made sure real stuntmen got plenty of work on the show.
Initially, television executives were wary of doing a show about a stuntman who moonlights as a private investigator. They changed their minds when they heard a demo tape of Lee Majors singing "The Unknown Stuntman".
Stunts took their toll on the GMC trucks, so several different ones were used during the show's initial run, causing some inconsistencies in episodes. For instance, the 1980 truck in the pilot had two square headlights and a light tan interior. For the rest of the series, it almost always had the quad headlight configuration of 1981 and newer models, with a dark brown interior. The truck always appeared to be a long-bed model, but a short-bed model was used in a few episodes. After huge jumps destroyed several trucks, a jump truck was custom-built, with a mid-mounted engine and a reinforced frame and axles.
Colt's truck was an early 1980s GMC 4x4 pickup - specifically a Rounded-Line 1981 GMC K-2500 Wideside - with a six-inch lift and 37-inch Dick Cepek off-road tires mounted on a 16-inch chrome wagon-style wheel. It also had a custom-made chrome roll bar mounted with four off-road lights, and a custom chrome grille guard mounted with two off-road lights and a Warn winch. A secret compartment in the truck's bed was used to hide villains or weapons.
The theme song, "The Unknown Stuntman", became a minor hit in the early 1980s. It was credited to Lee Majors in the pilot, but was credited to Majors' character Colt Seavers in subsequent episodes. The lyrics include the line, "I've been seen with Farrah", a reference to Majors' ex-wife, Farrah Fawcett.
Farrah Fawcett: According to the E! True Hollywood Story (1996) biography of Lee Majors, Farrah Fawcett made an appearance in the pilot, against the advice of her friends and manager. Lee and Farrah had just completed a messy tabloid-ridden divorce. She appeared on the show to show the public that they were separating on good terms.