Singer Olivia Newton-John had hardly done any acting, and was terrified of the idea of starring in a big-budget musical. John Travolta (who was also a singer) was really supportive though, and sometimes when Newton-John made a mistake during filming, he would make it look like it was his fault and take the blame for it.

Stockard Channing was 34 when Grease was being made, and she was supposed to be playing a teenager. She was also the oldest of the main cast members.

A little bit of trivia - the Saran Wrap they are wrapping the car in during "Greased Lightning" is a blatant sexual reference (check out John Travolta rubbing it on his crotch). In the 50's, Saran Wrap was often used in lieu of condoms.

At the end of the group dance when Danny and Cha-Cha get the trophy, you can see Marty fall and she is unable to get up because she keeps stepping on her dress.

Jeff Conaway had to walk slightly stooped to make John Travolta appear taller.

Grease was released in Mexico under the name 'Vaselina'.

John Travolta made the "cool dude walk" that Danny uses up in the first scenes of filming trying to create a bad boy image.

Dinah Manoff (Marty) was the only main cast member who was of high school age during filming, she was 18.

Olivia Newton-John had to be sewn into her trousers at the end of the film as they were so tight. They were put on in the morning and she was not allowed to take them off or go to the restroom while they were on, as the crew would have to waste time sewing them back on.

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).

In the stage shows before Grease was made into a film, Jeff Conaway, who plays Kenickie, played Danny and John Travolta played Sonny. 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.

After Cha-Cha and Danny win the dance-off, and all the group including extras group together for the big finale and ending of the song, look for the girl in the green dress behind Vince Fontaine. As everybody gets up, her partner slyly kisses her foot and she laughs.

When grease lightning has just won the rally, the water in the place was really polluted and when Kenickie runs through you can see him really afraid of the water and almost tip-toeing through it.

In the pep rally scene where everyone is rushing up to see what Coach Calhoun has to say, you will see a brown-headed girl rush forward, and then you will see a hand reach out and pinch her bottom.

Apparently the producers originally wanted Danny to commit suicide at the end of the movie, for whatever reasons. However, the writers rejected this idea and so we got Danny and Sandy driving off in the 'Greased Lightning' car instead.

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.