Sir Ian McKellen enjoyed acting with Robert Downey Jr. in Le don du roi (1995), and asked him to play the part of Lord Rivers, expecting him to turn the role down as too small. To McKellen's surprise, Downey immediately cleared his diary, and took the part.
Sir Ian McKellen cites this movie as his proudest accomplishment because, apart from having played the title character many times on-stage, he organized the funding, executively produced, and co-wrote the screenplay for this movie adaptation.
Maggie Smith (The Duchess of York) played the mother of Ian McKellen (Richard III), Nigel Hawthorne (George, Duke of Clarence) and John Wood (Edward IV). In real life, however, she was less than five years older than McKellen, five years younger than Hawthorne and four years younger than Wood.
It was writer and director Richard Loncraine's idea to make the Duke of Clarence an amateur photographer, symbolizing that he was only recording events without understanding them.
Sir Ian McKellen made Queen Elizabeth an American, because this way, she and her family could be seen as social climbers, from commoners to royalty.