According to the "Making of My Left Foot" segment on the Special Edition DVD, Sir 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.
Many of the scenes were filmed through a mirror, as Sir Daniel Day-Lewis could only manipulate his right foot to perform the actions seen in the film.
Daniel Day-Lewis's method acting for the role famously consisted of him staying in character even when the cameras were not rolling. While many critics applauded his dedication to 'inhabiting' the character of Christy Brown, the film crew and technicians were apparently not impressed, feeling they were having to wheel the able-bodied actor around the set and over obstacles unnecessarily.
It is the only film ever to get an A+ rating from Entertainment Weekly.