In a 2004 interview, John Landis revealed that he was the puppeteer for Grover during the final sequence, as Frank Oz was busy operating Miss Piggy. Landis also noted that Tim Burton was also among the many puppeteers in the finale.
Jim Henson was determined to use the larger budget of a feature film to push the technological limits and capabilities of puppetry. One of the most difficult feats (and one that appears deceptively easy on-screen) was making Kermit ride a bicycle.
Edgar Bergen died shortly after his scene was shot in 1978. It held particular meaning for Jim Henson, who cited, on many occasions, how Bergen and his wooden sidekick, Charlie McCarthy, influenced his interest in puppetry. The end credits include a dedication to Bergen.
The illusion of Fozzie driving the Studebaker was achieved by having a little person drive the car via remote control from the trunk, using a television monitor to guide his steering. The puppeteers would lie on the seat or floor and not see a thing. The first time they tested it, the television monitor went on the blink, and the driver had to be talked through the scene by an assistant director on a walkie-talkie ("A little to the right, now, to the left...hold it...").
It took three Kermit the Frogs to do the opening "Rainbow Connection" scene. One of the Kermits used in "The Rainbow Connection" was a mechanical; you can tell by the way it strums the banjo, and the colors of Kermit's "skin".
When several celebrities, who were scheduled to do cameos, had to drop out due to scheduling conflicts, and others were brought in, Writer David Odell, was hired to re-write the script and make each new cameo fit. His work on the film led Jim Henson to offer Odell the job of writing the screenplay for The Dark Crystal (1982).
Orson Welles plays a studio executive named Lew Lord who draws up a standard rich-and-famous contract for The Muppets, a reference to real-life Producer Sir Lew Grade (later Lord Grade). When Jim Henson was trying to find a producer to make The Muppet Show (1976) happen, no American network understood, nor was interested in the concept, Grade recognized Henson's vision and made the show possible.
The closing reprise of "Rainbow Connection" featured a crowd of more than two hundred fifty Muppet characters, virtually every Muppet that had been created up to that point in time. According to Jim Henson Archivist Karen Falk: "One hundred thirty-seven puppeteers were enlisted from the Puppeteers of America (along with the regular Muppet performers) to perform every Muppet extant. Prior to the day-long filming of the shot, Henson gave the enthusiastic participants a lesson in the art of cinematic puppetry. Amazingly, it did take just one day." The Muppet Show Fan Club newsletter answered the question of "How did they do it?" They response was "There are two hundred fifty puppets in the last shot of the film, and they're all moving. How? One hundred fifty puppeteers in a six foot deep, seventeen foot wide pit, that's how. They were recruited through the Los Angeles Guild of The Puppeteers of America and almost every puppeteer west of the Rockies reported for pit duty."
When Animal accidentally eats Dr. Bunsen Honeydew's Insta-Grow pills, he memorably balloons through the roof. Jim Henson refused to use a normal puppet on a miniature set to accomplish this effect, so his crew had to construct a gigantic Animal head that measured sixty feet.
According to David Odell, shooting on the final number in the film was delayed because Paul Williams developed a case of writer's block. Jim Henson asked Odell to come up with some dummy lyrics so they could block out the scene. When Williams heard somebody else was doing his job, he suddenly managed to finish the song quickly.
The sequences where Fozzie, Kermit, Miss Piggy, and the gang cruise around in that old Studebaker seem effortless, but they were a logistical nightmare. Kermit and Piggy each required a puppeteer, Fozzie required two, they all needed monitors, and none of them could appear in the shot. So four men squeezed underneath the dashboard of the car with their video monitors to accomplish this movie magic, but the engineering didn't stop there. James Frawley told SF Gate that they also "had a little person in the back of the car, steering and driving. We had a video camera on the nose of the car so he could see where he was going."
Gonzo is ridiculed when he says he wants to go to Bombay (also known as Mumbai), India, to become a movie star. According to International Business Times, the Bollywood film industry in that region produces roughly twice as many movies a year as Hollywood. Jim Henson once said that they wanted Gonzo to dream of being a movie star in the least likely of places, unaware until the film was completed that India produces more movies per year than Hollywood.
As the camera pans across the entrance to the movie studio, "Doglion", the large, horned full-bodied Muppet with long, gray hair, can be seen walking through the lot. He is the first member of The Muppets to be shown on the big screen.
To have Kermit ride a bicycle in a full-body shot, a Kermit puppet with legs was posed onto the seat and his legs and arms were attached to the pedals and handlebars. An overhead crane with a marionette system held the bicycle through strong strings invisible to the camera, guiding the bicycle forward. The crane and system was out of the camera's frame of vision.
"I Hope That Somethin' Better Comes Along" is a rare duet between Rowlf and Kermit, because Jim Henson usually performed both characters. Kermit, a simple "glove" puppet, could be operated with one hand, but because of his design, Rowlf required two performers: Henson's right hand would control the mouth, his left hand would control Rowlf's left hand, while another puppeteer would operate the right hand--meaning that in order to perform both roles at once, Henson would need three hands. In order to achieve the duet, the two tracks were recorded separately by Jim, and then combined into one. Henson and another puppeteer performed Rowlf (who required a more dynamic performance), while Kermit, who only had to sit and "lip-sync" the number, was taken over by a third puppeteer, marking one of the rare times Henson entrusted Kermit's performance to someone other than himself.
"Movin' Right Along", "Never Before, Never Again", and "I Hope That Somethin' Better Comes Along" were shortened in the film, compared to their soundtrack versions, for continuity purposes. 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. In "Finale: The Magic Store", a line performed by Kermit in the film is sung by Fozzie on the soundtrack recording.
Several classic cars were specially selected by Jim Henson for appearances in the film. The most prominent were a pair of 1951 Studebaker Commander Coupes driven by Fozzie Bear in the film. One car was painted, but unmodified and driven by a person in the front seat. It was used for long, travelling shots. The second car was driven by a person in the trunk, who viewed the road through a television set. The television received its image from a camera located in the center nose of the car's front grille. This made it possible for Frank Oz to perform Fozzie Bear in the front seat, and have the character seemingly drive the car in close-up shots.
For the scene where Kermit has a desert revelation, James Frawley wanted to include a shooting star in the night sky. So the crew attached a Christmas tree light to a wire on the soundstage, and when they got the signal, shot it across the set.
The main obstacle the filmmakers were faced with during the development of this movie was whether the Muppets would transition seamlessly from television to film. In 1978, Director James Frawley, Jim Henson, and Frank Oz filmed several camera tests outside of London to test how the characters would appear in real-world locations.
Kermit imagines thousands of other frogs going around with tiny crutches. Real-life wild frog populations have suffered a decimating rash of leg deformities in the years since the film was made, some from pollution, and others from natural parasites or predators.
When Dr. Krassman brings in the "electronic cerebrectomy" machine to scramble Kermit's brain, there is a LED display on the front of the machine which reads "666". This is a number frequently associated with the Devil, and is an allusion to the sinister nature of the machine.