According to the "Making of My Left Foot" segment on the Special Edition DVD, Daniel Day-Lewis broke two ribs during filming from assuming the hunched-over position in his wheelchair for weeks of filming. He also would refuse to come out of character. On visits to the set canteen, other people would have to help him with food. On one visit from his English agent, Day-Lewis again refused to come out of character as Christy Brown, and his frustrated agent took off.
Composer Elmer Bernstein first met producer Noel Pearson when he visited Dublin in 1968, when Bernstein was scoring Where's Jack? (1969). They soon became firm friends and apparently encountered Christy Brown in a Dublin pub. Pearson told him of his plans to make a Brown biopic, and Bernstein promised that if he ever got to make it, he would compose the soundtrack for free. Over twenty years later, he fulfilled that promise.