In India, the color of saffron represents sacrifice. When someone says, "Main rang de basanti", ("paint me saffron") it means that person is ready to be sacrificed for a great cause. Saffron is also a predominant color in the movie.
Aamir Khan was initially uncertain about taking on the role of DJ, as he was in his 40s and DJ was a 25 year old Punjabi in the film. He eventually accepted, though, and hired a tutor to aid him in Punjabi speech and accents.
Arjun Rampal was signed to do the film, but was irritated with director, Rakeysh Omprakash Mehra's indecisiveness about what he wanted to do with the characters and the script. He called him "very confused" and "unprofessional" and dropped out. Arjun Rampal also stated his regret in even agreeing to do the film in that he lost a lot of good work in the three months he spent committed to it.
After rejecting the role of DJ, Shah Rukh Khan was also offered the role of Flight Lieutenant Ajay Rathod, but he couldn't do it owing to his busy schedule. Later Madhavan took the part, and this cameo turned out to be the best bet of Madhavan in his career in Bollywood.
Shah Rukh Khan was the original pick to play DJ, but the shooting for the film was in Delhi, and Khan was forced to decline because he was shooting Paheli (2005) at the time, and did not want to conflict schedules.
When Rakesh Mehra started the film in 2002, it was to be a Indo/ British production to be made in English and Hindi. Manoj Bajpayee was signed for Aamir Khan's role and Vivek Oberoi for Siddharth's role. Atul Kulkarni was signed too, but for which role was not specified.
The trivia item below may give away important plot points.
The film went under severe controversy - first there was some uncertainty over shooting appropriate scenes inside the Amritsar Golden Temple; then the Indian Air Force requested an advance screening and caused an uproar on scenes showing corruption in the Indian Government and Air Force and the cover-up of an accidental plane crash; and finally, the 20-second horse race was cut on claims of cruelty to animals from the Animal Welfare Board.