Film journalist Anupama Chopra's book on the film, Dilwale Dulhania Le Jayenge: A Modern Classic, reveals that before he became a filmmaker, Aditya Chopra kept several exhaustive diaries of all the Hindi films he saw from 1989 to 1991. These were written by hand in Sydenham notebooks.
Aditya Chopra was only 23 when he wrote DDLJ's script. In his first round, he imagined an American boy and an Indian girl falling in love across Europe. He didn't think it would be his first film, but rather his fourth or fifth.
The crazy piano tune played before the song 'Ruk Ja O Dil Deewane' has been played by writer-director Aditya Chopra. Music composer Lalit Pandit gave it go, but Chopra felt he sounded too good; Chopra wanted a much wilder tune.
Juhi Chawla is also a part of the film, though you'll have a hard time spotting her. She was one of the sleeping passengers on the seat behind Simran on the train in which the friends travel through Europe.
Anupam Kher’s character, Dharam Veer Malhotra, and his relationship with his son Raj is based on the camaraderie shared between Yash Chopra and his sons, Aditya and Uday.
Stylist Anaita Shroff-Adajania, who has a role in the film as Kajol's friend Sheena, came up with her own character name. She thought it suited the character. Shroff-Adajania also played the girl who was with Shah Rukh Khan on the bike during his introduction scene.
Shah Rukh Khan and Kajol agreed to be a part of Karan Johar's first film during the shooting of the song 'Tujhe Dekha Toh Yeh Jaana Sanam'. Johar was Chopra's assistant director along with Uday Chopra.
Raj's now iconic Harley-Davidson leather jacket cost $400. It was purchased in a California store by Uday Chopra before he returned to assist his brother on DDLJ.
'Mehendi Lagake Rakna' was originally called 'Payal Baccha Ke Chalna', a tune music composers Jatin-Lalit had played for Yash Chopra before DDLJ started filming.
Anupama Chopra’s book also divulges that Aditya Chopra's original screenplay for DDLJ has Shah Rukh Khan's character name as Rajnath, the same name as Rishi Kapoor in Raj Kapoor's Bobby (1973).