Trivia: In the stage shows before Grease was made into a film, Jeff Conaway, who plays Kenickie, played Danny and John Travolta played Doody. Richard Gere also auditioned to play Danny in the movie, but John was given the part because of his role in 'Saturday Night Fever'. Also Didi Conn, who plays Frenchy, wanted to play Rizzo.
Trivia: Jamie Donnelly (Jan) had to dye her hair black daily during the shoot as she had prematurely grey hair.
Trivia: Dinah Manoff (Marty) could not dance at all, so they left her out of all the big dance numbers.
Trivia: Towards the end of the film, we see a group of students rushing out of Rydell High and onto the fields for the Graduation Carnival. All of these 'students' were winners of a contest which producer Allan Carr had organised and director Randal Kleiser chose the graduation scene as the right moment.
Trivia: Singer Olivia Newton-John had hardly done any acting, and was terrified of starring in a big-budget musical. John Travolta (who was also a singer) was really supportive, and when Newton-John made a mistake during filming, he would make it look like it was his fault and take the blame for it.
Trivia: Dinah Manoff (Marty) was the only main cast member who was of high school age during filming, she was 18.
Trivia: During the dance, Marty, the girl in the green strapless dress, is talking to the TV presenter next to the camera or something. Just at the end of the scene, she turns, and you can just see the top of her dress fall down quickly. It's only for half a second, so you have to look really carefully.
Trivia: During the dance, Danny is shown dancing with Sandy and singing a portion of the song "Those Magic Changes." Sandy then says he's very good and that he should take singing up professionally. This is a reference to the fact that John Travolta played Doody on Broadway before going on to play Danny in the movie. (Doody sings "Those Magic Changes" in the stage version. The song was used as a dance number in the film).