"The Muppet Movie" defined many a childhood, showing Muppet lovers the world over how Kermit and the gang first came together and signed their standard "rich and famous" contract. Four decades later, the music, humor and heartwarming origin story still resonate as strongly as ever. So celebrate this Muppet milestone by learning more about the making of this cinematic spinoff.

1. The movie was filmed during a break in the middle of Season 3 of "The Muppet Show."

2.Jim Henson saw the feature film budget as an opportunity to push the limits of Muppet technology. "The Muppet Movie" became the first film to feature 100% of a hand puppet's body onscreen while acting.

3. Henson revealed that the shot featuring Kermit riding a bicycle was among the most difficult technical challenges in the entire film.

4. The opening scene with Kermit playing guitar in the swamp was another major challenge. It took five days to film, with Henson forced to spend much of the time inside a 50-gallon tank underwater.

5. While Frank Oz performs many of the Muppet roles in the film (including Miss Piggy, Fozzie Bear, Animal and Sam Eagle), he also has a cameo as the biker who fights Fozzie in El Sleezo Café.

6. For the scene where Animal becomes a giant after eating Bunson's Insta-Grow pills, Henson insisted on actually constructing a 60-foot-tall version of the Animal puppet.

7. The musical number "I Hope Somethin' Better Comes Along" is a rarity for the franchise, as Rowlf and Kermit don't usually have duets together because Henson usually performed both characters. That scene is one of the few where Henson turned over the Kermit role to another performer during his life.

8.Orson Welles' character Lew Lord is a tribute to producer Sir Lew Grade, who was instrumental in helping "The Muppet Show" find funding.

9. "The Muppet Movie" also features an early, uncredited performance from Tim Burton. Burton is one of 137 puppeteers contributing to the final shot in the movie.

10.John Landis also chipped in for that shot, performing the puppeteer work for Grover so Oz could play Miss Piggy.

11. There are currently seven feature-length sequels to "The Muppet Movie," with the most recent being 2014's "Muppets Most Wanted."

"The Muppet Movie" is playing in theaters nationwide on July 25 and 30 for its 40th anniversary. Tickets are on sale now!