Five St. Bernards were used, one mechanical head, and a guy in a dog costume.
The dogs featured in the film would often have their tails tied down to their legs because the dogs would be enjoying themselves so much that they would wag their tails during filming. This tactic was missed once in the editing where they show Cujo from behind ready to attack and his tail is wagging energetically.
To make the St. Bernards attack the car, animal trainers put the dog's favorite toys inside the car so the dogs would try to get them.
Danny Pintauro actually bit Dee Wallace's fingers during his seizure scenes. Dee's reactions in the scene were quite real.
Stephen King has admitted several times that he was so into his alcohol addiction at the time that he does not remember writing the book.
The foam around Cujo's mouth was made of a concoction of egg whites and sugar. The dogs caused problems on the set by constantly licking the tasty stuff off.
After the film Dee Wallace went on record saying she hoped she'd never see another Pinto in her life.
Stephen King has stated that he feels Dee Wallace gives the best performance in this film of any film or TV adaptation of his books, including Kathy Bates's Oscar-winning turn in Misery (1990).
A rottweiller was used for some of the scenes because they couldn't get the St. Bernard to look mean enough.
Young star Danny Pintauro was only six years old at the time of the movie and had not learned how to read yet. He would often have to memorize his lines from the script with the help of his mother who was always close by on location.
Stars Dee Wallace and Christopher Stone were married at the time of the film.
Star Dee Wallace said she has often been praised by parents for the scene where a hysterical Donna screams at Tad in a moment of frustrated terror. She said its a scene only a parent could identify with.
The fog in the scene where Brett encounters a sick Cujo was created by a naval fog machine. The smoke brought out the local fire department who feared the woods were burning.
A rumor has circulated that "Cujo" is an ancient Indian word meaning "unstoppable force." In reality, Stephen King made it up himself when writing the novel.
Stephen King cites this film as having the most effective scare of any of the movies based on his works, referring to the jolting scare where Cujo first leaps at the passenger window of the car.
The character Sherrif Bannerman also appears in The Dead Zone (1983), played by Tom Skerritt. The original novel functions as an indirect sequel, as the serial killer Frank Dodd is mentioned several times, and may have possessed Cujo.
The story was inspired to Stephen King when he met his mechanic's intimidating dog while having his motorcycle repaired one day.
The original novel was a sequel of sorts following The Dead Zone. Since killer Frank Dodd was killed he became a kind of bogeyman in Castle Rock and supposedly haunted Tad. It is hinted that Dodd possessed Cujo. Sheriff George Bannerman, played by Sandy Ward here, makes specific references to Dead Zone hero Johnny Smith. Both this movie and The Dead Zone (1983) were developed at the same time, with this film released two months before, by different studios so the references were removed.
Stunt double Jean Coulter was in the car and had one of the toys used by the dogs' trainers as a "lure". The window was partially down, the dog jumped up and put his paws on the window, forcing it down and he reached in for his toy. Jeannie's reaction was to lower the toy and the dog bit her nose. She was treated at the hospital and released. There was also the rumor at the time that she was bitten by a rabid dog which was entirely incorrect.
Tad has a stuffed St. Bernard in his room, seen clearly in his first bedroom scene.
Donna takes Tad into the house for his nap, after Vic fails to fix the car. The camera moves to a view of the woodlands and ocean in front of the house. The woodland area is the same location where The Howling was filmed, also starting Dee Wallace.
Stephen King contributed substantially to the script but eventually declined Writer's Guild credit.
The St. Bernard that was featured the most in the film died of bloat during production.
The scenes where Donna and Tad are trapped by Cujo are suppose to be sweltering hot and appear that way on film. Yet the conditions were actually very cold during filming. At one point it got so cold inside the car that heaters were placed inside to keep the actors warm, but they would have to be turned off for shooting to prevent their sound from interfering.
The film debut for Danny Pintauro.
Shot in the same Mendocino, California community as the film Dead and Buried (1981). In fact in one shot the Pinto can be seen driving past the same church, with the 'reaper' shaped steeple, that's featured in Dead & Buried.
Karo syrup dyed red was used for fake blood.
Director Lewis Teague was recommended by Stephen King himself after seeing Teague's previous film Alligator (1980).
Ranked #58 on Bravo's 100 Scariest Movies countdown.
First film to take place in the fictional town of Castle Rock, which would go on to feature in The Dead Zone (1983), Stand by Me (1986), The Dark Half (1993) and Needful Things (1993). Rob Reiner, who directed Stand by Me and produced Needful Things, also named his production company Castle Rock.
A number of cars were used for the filming, each was disassembled for specific camera shots.
The exterior of the Trenton house was a facade.
The 360 degree pan around the car interior appears, judging by the major drop in picture quality, to have been shot on 16mm instead of 35mm.
The feature film debut for star Daniel Hugh Kelly.
Lewis Teague took over from Peter Medak.
The pinto was a 1978 Ford Pinto Runabout.
At one point the script for Cujo came to acclaimed horror director John Carpenter, however, Carpenter passed on directing as he didn't find the story particularly appealing. John Carpenter would later direct the Stephen King-based film Christine which came out the same year as Cujo.
In the original Stephen King novel, Tad Trenton dies of dehydration while Donna contracts rabies from her fight with Cujo. There was a rabies scare following the incident, not mentioned in the film. The outcome of the Sharp account was not mentioned, in the book he had saved it.
Stephen King said that if he could go back and change anything from one of his books it would be letting Tad live. This is why he survives in this film.
Sherriff Bannerman's death is the reason Castle Rock has a new Sherriff in subsequent films. The new Sherriff, Alan Pangborn, appears in The Dark Half (1993) (played by Michael Rooker and Needful Things (1993) (played by Ed Harris).
The house is across the street from Casey Becker's house in Scream (1996)