The original title of the film was "Kyon! Ho Gaya Na Pyar..." But the director felt the word pyar (love) was very common and used too often in Hindi films. So he restricted his movies title, by removing the word pyar from the movie.
Amitabh Bachchan was approached 10 times for the role, he turned it down each time. Eventually he accepted the film with the condition that the producer Boney Kapoor signs his son Abhishek Bachchan for the main lead role in Run (2004).
The real life relationship of the main lead 'Vivek Oberoi' and Aishwarya Rai Bachchan, has given the film the extra publicity, as this is a very much talked issue currently within the Bollywood industry and its fans.
While in production the movie got delayed because of the accidents the main lead had to face on the sets of their other movies, 'Vivek Oberoi' in Yuva (2004) and Aishwarya Rai Bachchan in Khakee (2004)
The reason why Amar Singh (politician) was thanked in the opening credits of the movie was because while Boney Kapoor was making Pukar (2000) he fell into financial problems and Amar Singh guided him. Boney Kapoor decided to thank him in all his movies for his unforgettable assistance in times of needs.