Development Farhan Akhtar conceived the idea to remake the
1978 film of the same name after listening to a remixed version of a song from the original film. The director co-wrote the film with his father,
Javed Akhtar, who had also written the original film with
Salim Khan. Akhtar revealed that the reason behind the remake was a desire to give a new treatment to "a fantastic film which he enjoyed watching as a child", and create an adaptation that he thought would suit modern times. Additionally, he wanted to pay tribute to the stars and makers of the original film, the 1970s era in general, and the films made by
Salim–Javed and
Amitabh Bachchan. In order to suit the modern sensibility, several changes were introduced. Akhtar changed a number of aspects of the climax as he felt the original ending was outdated for today's audiences. On the other hand, a number of elements from the original were retained in the new film, notably the background score, two songs, some dialogue, and some situations, all of which Akhtar believed were fine in the original, saying that not including them would be a crime. However, Akhtar felt that the character required a more mature actor, saying he wanted "a face that had seen the world and roughed it out." The director said that Roshan's innocence was not right for the role, and instead cast
Shah Rukh Khan for the part that had been portrayed by Amitabh Bachchan in the 1978 film. Akhtar found Chopra to be perfect for the role, saying, "There is a docile sensuality about her which suits the character." When he offered the role to her, she was excited to play the character and immediately agreed to do the film. While Rampal was cast as Jasjit, played by
Pran in the original, after
Akshay Kumar turned down the role for being secondary, Koppikar was cast in a completely new role that was not in the original film. In August 2005,
Kareena Kapoor was confirmed to appear in the song "Yeh Mera Dil", which had been performed by
Helen in the original film. Khan, Chopra, and Rampal underwent extensive
martial arts training from an expert from the
Shaolin Temple. Khan revealed that he had always wanted to look the way Amitabh Bachchan had in his films, but he said he gave his own interpretation to the role. Having seen the original film as a teenager, Chopra avoided watching the film again as she did not wanted to imitate Zeenat Aman's portrayal of Roma. She made a conscious effort to give her own look and style to the character. This was Chopra's first action role, and she was excited to the part, so she wanted to do all the stunts by herself.
Filming Principal photography commenced in February 2006 in central
Mumbai.
Art direction was handled by
Aradhana Seth, and the costumes were designed by
Aki Narula. Akhtar chose
K. U. Mohanan to handle the cinematography after having been impressed by his work in documentaries and TV commercials. To give an authentic feel to the film, scenes were shot on a closed set in actual
chawls in real locations. The filming moved to
Kuala Lumpur,
Malaysia, in April 2006 where the majority of the film was shot. 80% of the filming was done in Kuala Lumpur and
Langkawi. In Malaysia, filming was done over the course of 70 days at 42 locations including
KLCC,
Kampung Baru, and
Penchala Link, and included more than 1000 extras, all of whom were selected following auditions. Additional filming was done in
Singapore. Apparently, the former Prime Minister of Malaysia
Mahathir Mohamad, who had previously declined even Hollywood films to be filmed in the
Petronas Towers, gave his permission for the crew to film inside his personal office in the Towers. For a scene depicting a media ambush, several real-life journalists from India and Malaysia were hired. The song "Yeh Mera Dil" was choreographed by
Farah Khan. The song was filmed in Malaysia on 13 May 2006 with Khan and Chopra. ==Music==