Rizzo's hickeys were real. Stockard Channing said in an interview that Jeff Conaway insisted on applying them himself.
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. Ironically, the slumber party scene in the movie, and the song, was filmed on August 16th, 1977, the day Presley died.
In 2019, Dame Olivia Newton-John auctioned the leather jacket and pants she wore in the finale for $405,700, for the benefit of her cancer research charity. Spanx founder Sara Blakely bought the pants. The anonymous winning bidder of the leather jacket, which sold for $243,200, later returned it to Olivia.
Jeff Conaway was so infatuated with Dame Olivia Newton-John he was tongue-tied whenever she was around. He later married Olivia's sister, Rona Newton-John.
While shooting the "Greased Lightning" musical number, Jeff Conaway was accidentally dropped, hurting his back. Conaway started taking pain killers, eventually abusing prescription drugs, and spiralling into drug addiction until he died in 2011 at the age of sixty.
Patricia Birch: The Choreographer, and Director of Grease 2 (1982), is one of the dancers during the contest.
Michael Biehn: When Danny (John Travolta) and Kenickie (Jeff Conaway) put the frog in Patty's (Susan Buckner's) bag. NOTE: This is not a cameo appearance, which happens after an actor or actress has achieved success. This was simply an uncredited appearance early in Biehn's career, while he was still a struggling actor.