The song "Chale Jaise Hawaein" was shot in one take.
The first stunt Shah Rukh Khan does while walking on the wall was a secret from director Farah Khan. She didn't want him to do that stunt due to his back injury. She even threatened to tell his wife, Gauri Khan.
Farah Khan wanted Naseeruddin Shah to play Raghavan, but due to his commitment to La leggenda degli uomini straordinari (2003) he was not able to take on such a large role at that point of time. Hence, his special appearance as Shah Rukh Khan's father. For the role of Raghavan, Farah Khan subsequently approached Kamal Haasan, who couldn't give dates either. Then, Nana Patekar was approached, who demanded certain changes to the story of the film, which Farah Khan was not willing to do. Only then Suniel Shetty was approached.
Shah Rukh Khan originally did not like the title of the movie believing it sounded incomplete. It was not until he heard the title song, when he believed the title was perfect.
Sushmita Sen's reaction when Srk shoots through her saree was natural as it was taken without telling her.