The casting of Brazilian model Giselli Monteiro as Harleen Kaur was considered an unlikely choice. Imtiaz had said, “Giselle came to me through dress designer Anaita Shroff. She was to play Jo, Saif’s Caucasian girlfriend in the second-half. She wasn’t right for Jo. But my wife (Preety Ali), who was there, suggested Giselle for Harleen.”

Did you know, the film originally ended on an unhappy note? Saif had shared, “We had a sad ending at first and then Imtiaz relented and gave us a happy ending. I now wonder, which is better? I think Jai deserved to lose Meera, but we were worried about being too clever.”

When a sequel was announced, actor Saif Ali Khan wasn’t interested in doing it and had said, “I don’t see it as a continuation... Imtiaz should probably try and make one of these every 10 years, calling it Aaj Kal with different actors! I’m hoping it is a different story, though.” Incidentally, his daughter, actor Sara Ali Khan acted in the film’s spiritual sequel, Love Aaj Kal (2020).

Saif wanted then-girlfriend actor Kareena Kapoor Khan to be cast opposite him. Saif had said, “I think, she was quite keen to work with Imtiaz Ali again and I think he promised her his next movie. Her boyfriend being the producer of Imtiaz’s next movie and being in the situation that she was, she was wondering and finding it hard to understand why we had cast Deepika, I think.”

Imtiaz later admitted that “casting Deepika was a risk”: “It was a challenge to myself as Deepika was a newcomer.” Imtiaz was so sure about his casting choice that he offered Meera’s role to Deepika even before she committed to making acting her career.

This love story had received the stamp of approval from late filmmaker Yash Chopra. In an interview, Imtiaz had shared, “I remember that Yash ji had called me after watching it. I had rushed away from the room I was in, and went to the balcony to hear very carefully what he was trying to say. He liked the film, that was a great moment for me.”

Actor Neetu Kapoor made a cameo appearance, returning to screen after 26 years. Imtiaz had revealed, “I fell on my knees and told her I am a huge fan. After a lot of persuasion, I finally convinced her to act in my film.” Neetu later said that she did the film “as a favour” to Rishi.

- The working title was Production No 1, because it was Saif Ali Khan’s first production. Later Aaj Kal, and Elastic were considered as titles.

- While shooting for the song Chor Bazari, Deepika Padukone met with an accident. In the scene where she is supposed to fall from a table and land in Saif’s arms, the actor ended up on the floor, but avoided serious injuries.

- The songs Aaj Din Chadheya and Aahun Aahun were initially not a part of the film. But composer Pritam convinced Imtiaz Ali to include them, saying that the film needed a romantic track.

- The film was remade in Telugu in 2011, titled Teen Maar and starred Pawan Kalyan, Trisha Krishnan and Kriti Kharbanda.