Celebrating 45 years since its release, "Grease" continues to captivate audiences. The film's enduring love story between Sandy Olsson (Olivia Newton-John) and Danny Zuko (John Travolta) has made them cultural icons. But the journey to create this cinematic masterpiece involved unexpected twists, casting dilemmas, and musical improvisations.

Olivia Newton-John almost declined the role of Sandy due to past film experiences. Casting director Joel Thurm revealed that Travolta championed Newton-John, but she requested a screen test – a rare occurrence for a star of her stature. The screen test reassured her, and thankfully, there was no backup plan. Newton-John even had to be sewn into her iconic leather pants daily due to their age and fragility.

Director Randal Kleiser shared how the drive-in scene involved improvisation, with a last-minute decision to synchronize a hot dog jumping into a bun with the music. Travolta wasn't the initial choice for "Greased Lightning," but he secured the role due to his influence. The iconic duet "You're the One That I Want" was a last-minute addition, while Stockard Channing fought to keep Rizzo's poignant solo "There Are Worse Things I Could Do."

Casting was another intriguing aspect. Elvis Presley was considered for the Teen Angel but declined, and the role went to Frankie Avalon. Henry Winkler, known for Fonzie, turned down Danny Zuko to avoid typecasting. Carrie Fisher was even briefly considered. John Travolta's sister, Ellen, landed a cameo after visiting the set.

Surprisingly, "Grease" was almost an X-rated cartoon. Ralph Bakshi, known for "Fritz the Cat," expressed interest, but Allan Carr ultimately secured the rights. The film's unexpected success overshadowed "Sgt. Pepper's Lonely Hearts Club Band," which the studio had predicted would be the bigger hit.