Produced during the third season of The Muppet Show, the film tells the origin story of the Muppets, as Kermit the Frog embarks on a cross-country trip to Los Angeles, encountering several of the Muppets—who all share the same ambition of finding success in professional show business—along the way while being pursued by Doc Hopper, a greedy restaurateur with intentions of employing Kermit as a spokesperson for his frog legs business.

The film stars Muppet performers Henson, Frank Oz, Jerry Nelson, Richard Hunt, and Dave Goelz, as well as Charles Durning and Austin Pendleton, and it features cameo appearances by Bob Hope, Dom DeLuise, James Coburn, Cloris Leachman, Richard Pryor, Telly Savalas, Edgar Bergen (in his final film appearance before his death), Orson Welles, Carol Kane, Steve Martin, and Mel Brooks, among others.

The film received critical praise, including two Academy Award nominations for Paul Williams and Kenneth Ascher's musical score and their song, "Rainbow Connection".

After he plays his banjo and sings "Rainbow Connection", he is approached by Bernie, a talent agent who encourages him to pursue a career in show business.

Joined by Rowlf the Dog and reunited with Miss Piggy, the Muppets continue their journey to Hollywood, but their car breaks down in the desert.

Kermit and his friends are saved when one of Dr. Honeydew's inventions, "insta-grow" pills, enlarges Mayhem drummer Animal, who frightens away Hopper and his henchmen.

[12][13] Along with Frank Oz and the team, they filmed and tested how the characters would appear in real-world locations during the first few days of June 1978 in a UK meadow.

[11][12][13][14][15] During filming tests, a cow was ambled near Fozzie for an unexpected rear look at a comparison between fake and natural fur hair.

A dancing Kermit and Fozzie Bear were operated by Henson and Oz in front of a blue screen, and they were composited onto a separate reel of the stage.

[citation needed] For scenes involving Fozzie driving a Studebaker, cables, TV monitors, puppeteers, and its Muppets were filled in.

[8][28] Prior to the day-long filming of the shot, Henson gave the enthusiastic participants a lesson in the art of cinematic puppetry.

[8][28] In September 1978, Edgar Bergen, Henson's idol who appeared in a cameo role, died shortly after completing his scenes.

[citation needed] The latter, a duet between Rowlf and Kermit, contained references that the studio considered too mature for children, although the song appeared complete in the British theatrical and home video debut versions.

[citation needed] The Muppet Movie had a royal premiere at the Leicester Square Theatre in London on May 31, 1979, attended by Princess Anne.

[42][43] In Austin, Texas, then-CBS affiliate KTBC-TV and American International Traveler sponsored a contest where adults who paid to see the film in the area were eligible to win a free trip to Hollywood.

The site's consensus says "The Muppet Movie, the big-screen debut of Jim Henson's plush creations, is smart, lighthearted, and fun for all ages.

"[54] Vincent Canby of The New York Times offered equal praise, stating that the film "demonstrates once again that there's always room in movies for unbridled amiability when it is governed by intelligence and wit.

Script by Jerry Juhl and Jack Burns incorporates the zingy one-liners and bad puns that have become the teleseries' trade mark, but also develops the Muppets themselves as thinking, feeling characters.

"[57] Kathleen Carroll of the New York Daily News wrote that "with the exception of Brooks' wacky scene and Steve Martin's funny bit as a snooty waiter, the cameo appearances by such stars as Bob Hope and Richard Pryor tend to slow the action down just as the bland musical numbers by Paul Williams and Kenny Asher interrupt the flow of the movie.

"[58] Rex Reed, in the same newspaper, reacted more enthusiastically to the film, remarking that "if there's any doubt, The Muppet Movie will make believers and fans out of the worst pessimists.

"[59] Charles Champlin of the Los Angeles Times wrote, "as you might well expect, it is hip, funny, technically ingenious, fast-moving, melodious, richly produced, contemporary and equally and utterly beguiling to grown-ups and small persons.

"[61] John Skow of Time magazine offered a more mixed response, saying that "the transition from the yank-'em-off-if-they-bomb lunacy of the TV show to the coherent narration of the film is not a complete success.

Muppet magic remains a bewildering succession of wonderful bits, and perhaps the movie's best occurs when Rowlf the Dog, who is a barroom pianist, commiserates with Kermit, who has just been deserted by Miss Piggy.

"[62] Michael Hanton of the Toronto Star wrote that "I was looking forward to a combination of Singin' in the Rain, Citizen Kane, and Intolerance.

What I got was more like Gidget, The Great Race and Love Boat"; he also remarked that Fozzie Bear stole the show from his favorite character, Miss Piggy.

Tim Radford of The Guardian called it "another film spun slightly longer than it should have been", adding that "the humour remains decently dry and self-deprecating throughout; on the other hand there isn't nearly enough of it, and a good 40 or 50 minute idea is padded to the obligatory hour and a half with songs, travelogue, flashbacks and a certain amount of mooning about.

He also said that "the style is cunningly varied at intervals by the appearance in virtually two-line parts of such people as Milton Berle, James Coburn, Dom DeLuise or Elliott Gould, not to mention Orson Welles, each in his own comic persona.

"[65] Alexander Walker of the London Evening Standard supplied the film with its most positive review in the country, calling it "the most original little show in town, and adding that it offered:Across the board delight: not only for the children: for adults, too, who'll relish its in-jokes, visual wit, cheeky parodies of other movies and [its] own brand of surrealist fun.

The Muppets "magic," supplied by creator-producer Jim Henson and other talented artists operating the globe puppets from hiding places that a sewer rat would think cramped, endow their stars with independent life and liveliness.

"[75] In 2020, "Rainbow Connection" was deemed "culturally, historically, or aesthetically significant" by the Library of Congress and selected for preservation in the National Recording Registry.