I love this piece from the Cinema Shorthand Society:

On this date in 1981, "Ragtime" was released.
Jack Nicholson had to drop out of the film less than a month before filming began, leaving the producers without a name star. Director Milos Forman recruited James Cagney, who he had met the year before at a private dinner in Connecticut. He offered Cagney any part he wanted, including (facetiously) Evelyn Nesbitt.

According to Forman, Cagney initially agreed to play New York City Police Commissioner Rhinelander Waldo on two conditions: he would not sign a contract of any kind, and he reserved the right to change his mind and quit the film until three days before shooting began on his scenes.

Cagney had been advised by his doctors and caregivers that making a film at this point in his life was very important for his health. The actor never flew, so he and his wife took an ocean liner to London, where his scenes were filmed. Despite his numerous infirmities, he stayed on set during his fellow actors' close ups to give them line readings. Because of the presence of the ailing Cagney, in what became his final big screen appearance, the movie was officially exempted from the long-running actors' strike of the early 1980s. It was the only production to receive that honor.

Cagney used a wheelchair at the time of shooting. Most scenes show him sitting. A stand-in was used for scenes showing him on his feet, shot from the back to obscure the stand-in's face.

Cagney was 81 when he filmed this movie. His character, Commissioner Rhinelander Waldo, was 32 at the time in which the movie was set.
This film reunited Cagney with Pat O'Brien (photo below), his frequent co-star from the 1930s and 1940s. It was the last theatrical film for both of them. In addition, Forman hired Donald O'Connor at the request of Cagney. O'Connor had been having personal and professional problems, and Cagney wanted to help him.(IMDb)