This ended up becoming the most financially successful independent motion picture of 1976, earning an impressive thirty-nine million dollars worldwide in box-office revenue, breaking records as well. It held this record for two solid years, until Halloween (1978) broke it.

After the film had been distributed worldwide and had grossed thirty-nine million dollars, which made it the most successful independent motion picture of 1976, the film's distributor, Edward L. Montoro, and his company, Film Ventures International, decided to keep the profits without paying Director William Girdler and the film's Producers and Writers David Sheldon and Harvey Flaxman. They sued, and Montoro was eventually ordered by the Los Angeles County Superior Court to pay the box-office proceeds due to Girdler, Sheldon, and Flaxman.

A bear, who was nicknamed "Teddy," played the title role. Teddy stood eleven feet tall, was the largest grizzly bear in captivity at that time, and was untamed, but trained by the bear's trainer. The crew was protected from Teddy by an electrical thin green wire that ran throughout the forest locations. In addition, a mechanical bear was used for when the bear had attacked.

A separate, unrelated independent horror film about a killer grizzly bear in Alaska, Claws (1977), was re-released in 1978 in Canada and Mexico as Grizzly 2 to capitalize on the success of this film and Jaws.

The entire cast, crew, extras, bystanders, and on-lookers were all forbidden from going anywhere near the bear.

Edward L. Montoro never paid any of the SAG actors any residuals, and fled the country.

The original poster art for this movie was by comic book artist Neal Adams.

Day of the Animals (1977), released the following year, was sometimes mistaken as a sequel to this movie, mostly because it has basically the same plot, cause, "Teddy" bear actor, Director William Girdler, production and distribution company, Producer Edward L. Montoro, and also starred Richard Jaeckel and Christopher George.

The movie was filmed from the week before Thanksgiving and the five weeks afterward, and "Teddy" was getting ready to hibernate . At times, he was grumpy because of that. During one long dolly shot, his trainer dangled a big fish on a pole in front of him, then switched it out with a smaller fish at the end of the run. Bears are not all that bright, but by the seventh take, "Teddy" had wised up, and he suddenly wheeled toward the camera, ran about thirty feet, stood up, and snatched the big fish off of the pole, which took about three seconds.

A sequel to this movie was filmed and partially completed during the early 1980s, but never released. Grizzly II: Revenge (2020), also unofficially known as "Grizzly II: The Predator," was never properly completed and never released into theaters, home video or DVD. A work print of it has surfaced of it on the Internet.

The idea for the film came from Writer Harvey Flaxman. When he was younger, he had an encounter with a grizzly bear on a camping trip. He thought it would be a great idea for an animal attack film. Flaxman and David Sheldon eventually came up with the script, which was then made into this movie.

Robert O. Ragland conducted the National Philharmonic Orchestra of London, but used only twelve of the lowest sounding instruments for the bear's stalking theme.

Edward L. Montoro once said of this movie for the film's publicity: "The Grizzly is the largest carnivorous ground beast in the world, and one of the most dangerous animals to walk this Earth. It is a popular misconception that Grizzlies are placid, fruit and insect-eating animals. Rather, they are foul-tempered, and basically meat-eaters. Bears of all kinds kill and maim people all around the world."

The height and weight of the Grizzly, according to the film's publicity, was eighteen feet and two thousand pounds. However, the height of the Grizzly in the film's story line was around three feet shorter, said to be at or at least fifteen feet, thereby somewhat making the movie's promotional blurbs an exaggeration. Moreover, the height of the Grizzly, called "Teddy," that portrayed the ferocious beast in the film, was only eleven feet tall, seven feet less than its publicized eighteen feet.

Warner Brothers originally expressed interest in financing the film and was reportedly furious that Edward L. Montoro and Film Ventures International (FVI) had taken the project. Warner Brothers offered to put up a larger budget. The year before, the studio sued Montoro and FVI over copyright infringement, for the successful theatrical release of The Exorcist (1973) rip-off, Beyond the Door (1974).

Many of the local residents of Clayton, Georgia appear in the movie as extras.

Ben Johnson was the first to be offered the part of Don Stober (Andrew Prine).

The film's plot and story structure mirrors Jaws, effectively becoming Jaws on land. Many of the exact same story beats from Jaws are almost shot for shot reproduced in Grizzly.

One of the first victims was portrayed by Kathy Rickman, who was the daughter of real-life Clayton, Georgia mountain man, Frank Rickman.

The novelization actually gave real reasons for why the bear started eating people. It grew too big too fast, so its mother drove it off before it knew how to hunt properly. It injured its jaw before entering the park, leaving it in serious pain, and one of the first victims was menstruating.

Two different bears were used: an eleven-foot Grizzly bear and a seven-foot Black bear. To prevent injuries, the bears were kept separate from the actors and crew by a fence, and two stuntmen in costume were filmed for the bear attacks.

The zoological species name given for the Grizzly bear in the film's story is "pleistocene arctodus ursos horribilis," but this nomenclature is fictional. However, there is a similarly-named subspecies of North American brown bear, Ursus arctos horribilis, more commonly called the Mainland grizzly.

Second collaboration of Christopher George, Andrew Prine, and Richard Jaeckel. The first was Chisum (1970).

The location is supposedly a national park, but it is never identified.

A novelization of the film was written by Will Collins and published in 1976.

Clint Walker was first asked to play Ranger Kelly, but instead did Snowbeast (1977). Christopher George got the part of Kelly.

Riffed by the guys from Mystery Science Theater 3000 (1988) under the RiffTrax name, Michael J. Nelson, Bill Corbett, and Kevin Murphy.

When Christopher George gets out of the helicopter for the grizzly hunt, he has an M1 Garand rifle. Andrew Prine gives him a bolt action rifle, saying how it is a 30-06 with a K4Scope, better than his army rifle. The M1 is a 30-06 caliber also and holds 3 more rounds of ammo.

Debut produced screenplay of co-Writer David Sheldon, but the final produced screenplay of co-Writer Harvey Flaxman.

This film reunites Richard Jaeckel and Andrew Prine who both featured in The Devils Brigade released in 1968.

In an interview with Edward L. Montoro published in the May 1, 1984 edition of 'The Hollywood Reporter', Montoro said he thought this movie to be the best film that he ever produced.

The M1 is the first variant of the M1 Rocket launcher series and is actually an early WW2 vintage weapon and not a weapon that would have been used in Vietnam. In the film, the M1 Mockup is a little too short.

Harvey Flaxman: The Co-Screenwriter is a reporter by Charley Kittridge's (Joe Dorsey) office.