The dance contest scene was filmed during the summer, when the school was closed. The gym had no air conditioning and the doors had to be kept closed to control lighting, so the building became stifling hot. On more than one occasion, an extra had to be taken out due to heat-related illness.
In the stage play, the song "Look at Me, I'm Sandra Dee" had a reference to Sal Mineo, who was murdered in 1976. For the movie, the lyric was changed to reference Elvis Presley, who died the same day the scene was filmed.
"Hopelessly Devoted to You" was written and recorded after the movie had wrapped. The producers felt they needed a strong ballad and had Olivia Newton-John come back to film her singing this song. This song ended up receiving an Academy Award nomination.
Jeff Conaway stated in an episode of Celebrity Rehab with Dr. Drew (2008) that while filming the scene/song "Greased Lightning" he was dropped by his fellow cast members and injured his back leading to his addiction to prescription painkillers.
"Greased Lightning" was supposed to be sung by Jeff Conaway's character, Kenickie, as it is in the stage version. John Travolta used his clout to have his character sing it. The director felt it was only right to ask Conaway if it was okay. At first he refused, but he eventually gave in.
The original stage play had more sexual references than the censors wanted to allow. Among these was the use of plastic wrap as protection. To overcome the censors, there weren't any blatant references but Danny rubs plastic wrap over his crotch during "Greased Lightning".
When Olivia Newton-John was cast as Sandy, her character's background had to be changed to accommodate Newton-John's own background. In the original Broadway musical Sandy was an all-American girl and her last name was Dumbrowski. In the movie version, she became Sandy Olsson, foreign-exchange student from Australia. Also, because of Newton-John's casting, John Farrar (Newton-John's frequent songwriter) had to write two new songs for the film while other songs from the Broadway musical were dropped.
In the scene where the cast are near the bridge after the car race, the water on the ground was stagnant and dangerous. Some cast members became ill from filming as the setting was a derelict place full of dirt and rubbish.
Randal Kleiser shot a scene of Kenickie and Rizzo getting into a heated argument, which explained their attitude towards each other in the diner scene (where Rizzo threw the malt at Kenickie). The fight scene was cut because it didn't match the tone of the rest of the film; it was much grittier, described by one crew member as "looking like something Martin Scorsese might have directed."
The final musical scene, "You're the One That I Want" was filmed with the help of a traveling carnival. However, director Randal Kleiser decided the next day that additional scenes were needed for close-ups. Unfortunately the carnival had left town, so set decorators were called in to build replica backgrounds that matched the carnival ride's construction for the close-ups.
Olivia Newton-John requested to have a screen test before she accepted the role of Sandy. The director Randal Kleiser agreed and they shot the 'drive-in movie' scene with Danny and Sandy as a trial. Newton-John was pleased and went on with filming.
It was released again in theaters in 1998 for a couple of reasons: to mark the 20th anniversary of the original and because the year before, a dance mix of songs from the soundtrack became a big hit on radio.
The production had a product placement plan with Coca-Cola, but it fell through. The Coke products were taken out or blurred. There is a huge hanging picture/advertisement in the diner that was blurred out. Photos on the inside flaps of the soundtrack album have Pepsi products.
Several musical numbers were not used in the film. They appear, however, as jukebox tunes, or band numbers at the high school dance. Among them "Freddy, My Love", "Those Magic Changes", and "It's Raining on Prom Night" all of which were performed by characters in the stage musical.
Stockard Channing was not the first choice for the role of Rizzo; Lucie Arnaz was allegedly dropped from consideration when her mother, Lucille Ball, called Paramount and said, "I used to own that studio; my daughter's not doing a screen test!" (Ball actually owned the studio Desilu which was bought by Paramount). The part went to Channing when the casting director remembered seeing her with Lucie in the play, "Vanities" at the Mark Taper Forum in Los Angeles (the third member of the cast was Sandy Duncan).
Randal Kleiser felt the stream of consciousness lyrics Barry Gibb wrote for the opening theme were quite out of place and inappropriate for the light and fun movie he was making. But with Barry Gibb and his Bee Gee Brothers riding high with the Robert Stigwood organization from the Saturday Night Fever (1977) success and Kleiser being a young upstart director, he felt he had no clout to ask for any changes.
The original Broadway production opened at the Eden Theater on February 14, 1972 and ran for 3,388 performances, setting a record. Adrienne Barbeau and Barry Bostwick were in the original Broadway cast. John Travolta appeared at some time as a replacement on Broadway in the role of "Doody". Marilu Henner, an alumna of the original Chicago production, appeared as a replacement in the role of "Marty". Patrick Swayze and Treat Williams were both replacements as Danny Zuko. Richard Gere is also listed as an understudy to many male roles, including Danny Zuko. Gere played Zuko in the London production in 1973.
Jim Jacobs and Warren Casey, who wrote the original stage play, were originally supposed to serve as executive producers of the film but got kicked off the set by Allen Carr. Patricia Birch who was choreographer on the Broadway stage continued her role in the movie version and the film original song "Sandy" was co-written by Louis St. Louis who wrote some songs used in the film.
According to Didi Conn in an interview on KGO-AM, there were plans for a sequel named "Summer School" distinct from the well-known sequel Grease 2 but Paramount later nixed the idea. This idea grew out of Coach Calhoun's line "I'll see you in summer school" to a student after he is hit with a pie in the carnival scene near the end.