K.A.R.R. - (Knight Automated Roving Robot) aka the evil Trans Am, was the prototype for K.I.T.T. But its system had only been programed for self-prevail, were K.I.T.T. is programed to regard and prevail human life its "evil twin" was not. The voice of K.A.R.R. was done by voice actor Peter Cullen, who is probably best known as the voice of Optimus Prime of "The Transformers", Cullen has also been voice to "The Predator" and Eeyore of "Winnie Pooh".
Patricia MacPherson was fired after the first season and replaced with Rebecca Holden to add more sex appeal to the show. David Hasselhoff was unhappy with the change and lobbied the producers to hire McPherson back. McPherson returned in the third season.
KITT, the Knight Industries Two-Thousand, was a customized 1982 Pontiac Trans-Am. The 1982 model year was the first year of the third-generation (1982-1992) F-bodies (Chevrolet's Camaro and Pontiac's Firebird share the same platform), and was a complete redesign of the second-generation (see Smokey and the Bandit (1977) for a 2nd-gen Trans-Am).
Glen A. Larson borrowed the idea of K.I.T.T.'s hood mounted scanner from one of his earlier projects, 'Battlestar Galactica'. The Cylon Centurions in that series had an almost identical scanner that functioned as eyes, and Larson adapted the idea for K.I.T.T. Also, originally K.I.T.T. had a square red light on the dashboard that lit up as he spoke. His more familiar 'voice modulator', with three red lines broken into cells which went up and down as he spoke, was introduced half-way through the first season.
You never see a long shot of KITT changing into Super Pursuit Mode, since KITT is not moving at all. A shell of KITT's body was used when filming the transition to Super Pursuit Mode, since large hydraulic rams were needed to articulate the body panels, and there was no room for an engine or running gear in the car.
Throughout Season 1, there is another car that appears regularly besides the Knight Industries Two Thousand and Devon's Mercedes-Benz convertible. It is a red 1974 (or thereabouts) AMC Gremlin X, possibly one of the crew's personal vehicles. It was never used in a "supporting" role, but only as a vehicular "extra", usually driving away from the camera.
The second series saw the extensive use of miniatures provided by Jack Sessums for most of the really impossible stuff like jumping over trains, over helicopters, crashing into Goliath and "walking on water". The miniatures of KITT were made to 1/8th scale, modified from the existing commercially available Monogram kit of the 1982 Camaro Z-28 to the same scale. Almost everything done involving trains were miniatures built by Sessums and his crew, as it turns out Sessums was a model train enthusiast who had large scale garden railway models already built, and the production crews made a lot of use of these models which for the most part were ready for use. The same model trains were also used in The Fall Guy (1981) and other similar productions of the time.
The character of Michael Knight was originally known as Michael Long, a cop who is shot in the desert and left for dead. Recovered by Wilton Knight and Devon Miles of Knight Industries, Mr. Long then undergoes reconstructive plastic surgery on his face. He is given a second chance at life, joining the Knight Industries team donning a new a face and identity, he is Michael Knight, the Knight Rider. Other alias' include: Mr. Dugan, "Knight Rider: Inside Out (#1.9)"
K.I.T.T. has The roving Red sensor on the hood, It is not only modeled after The Cylon's roving eye from Battlestar Galactic but when it shown in a close up, and is moving, not only does it look like the Cylon eye, but also has the same sound effect of it moving as the Cylon's eye made.
Pontiac, who supplied the Trans Am for the series, found itself swamped with customer requests for black Firebird Trans Ams with T-tops, tan interiors, and red lights on the front bumper, just like the show car.
According to Brandon Tartikoff, the head of programming at NBC during the 1980s, the inspiration for the series came about when NBC executives started complaining about the problems of casting handsome leading men in TV series, because many of them couldn't act. Tartikoff and his assistant came up with a concept for a TV show called, "The Man of Six Words". Each show would begin with the leading man getting out of a woman's bed and saying, "Thank you." Occasionally, throughout the show, the leading man would say, "Okay," when receiving orders from his boss. Then he would chase down some villains and say "Freeze!" Finally, when the people he had saved from death would thank him, he would say, "You're welcome." For the rest of the show, the car would do all the talking. Although Tartikoff had meant the pitch to be a joke, the NBC executives liked the idea of a TV show about a man with a talking car, and approved it for development.
Much of the fan mail written to the series by younger viewers was addressed to the name Michael Knight. Some of these letters were accidentally sent to Actor Michael Knight, who was emerging as a popular cast member of the Daytime Drama All My Children. Knight subsequently added his middle initial E to his screen name to avoid confusion. Interestingly, the actor Michael Knight would later marry Catherine Hickland, who played Michael's love interest on Knight Rider, and was married to David Hasselhoff at the time of the series.