Before filming, Richard Attenborough turned down Geraldine James' request to have an audio recording of the real Madeleine Slade / Mirabehn as part of researching the role. Instead she was told to play it straight like a normal English woman. Later she discovered the reason: after filming she was allowed to listen to the recording (taped between Attenborough and Slade in Austria) only to discover that Slade talks with an Indian accent, having spent 34 years in India talking in Hindi as well. It was James' friend, casting director Susie Figgis who recommended her for the role.
Ben Kingsley's (born Krishna Bhanji) paternal family was from the Indian state of Gujarat, the same state Mohandas K. Gandhi was from. He took his stage name from the very same Kingsley Hall in London where Gandhi stayed on his visit in 1931.
300,000 extras appeared in the funeral sequence. About 200,000 were volunteers and 94,560 were paid a small fee (under contract). The sequence was filmed on 31st Jan 1981, the 33rd anniversary of Mohandas K. Gandhi's funeral. 11 crews shot over 20,000 feet of film, which was pared down to 125 seconds in the final release.
No studio was interested in financing the film. Richard Attenborough cited that most of the financing were solicited from: 1. Joseph E. Levine whom agreed to finance in exchange of Attenborough directing A Bridge Too Far (1977) and Magic (1978). 2. The sale of the ownership share of "The Mousetrap". 3. Jake Eberts, a friend of Attenborough. The remaining of the money were solicited from major companies in England minus the BBC.
For the funeral scene, advertisements calling for 400,000 extras were either distributed in pamphlets and by newspapers in Delhi. Extras were not allowed to wear anything other than white and as part of security measures, turnstiles were built at selected entry points for crowd control. The crew bought any clothing that was not white.