Francis Ford Coppola gave Robin Williams camping gear, to spend the night in his backyard, and $10 to spend at Toys R Us before shooting the film.
Robin Williams agreed to play Jack Powell after Disney apologized to him for breaking their promise to keep his name out of the marketing for Aladdín (1992).
Jack's condition is based on progeria, a real-life condition that causes rapid aging. The average lifespan of someone with progeria is 13; the oldest recorded lifespan (as of 2018) is 30.
Although ridiculed for making this film, Francis Ford Coppola has defended it, saying he is not ashamed of the final cut of the movie. He had been friends with Robin Williams for many years and had always wanted to work with him as an actor. When Williams was offered the screenplay for this film, he said he would only agree to do it if Coppola agreed to sign on as director.
After Ryan Acton, Robin Williams's photo double, was told he wasn't needed and allowed to go back to school, he was called back to the set. When Francis Ford Coppola asked him to get to makeup, Acton refused to get out of the car. Williams got into the car and talked to him. Acton got out of the car, went to makeup, and wasn't used for the day. A few years later, Acton revealed what Williams said, "Hi, Ryan, I am your funny double, and if you don't want to get out of the car, it's OK."