Dawson Casting: Russell Crowe was in his late 30s during the filming, which begins as Nash enters Princeton University. While his age is not stated in the movie, in reality this happened when Nash was 20 years old. Granted, Crowe plays him right up until he receives the Nobel Prize in his mid-sixties.
Romance on the Set: Jennifer Connelly and Paul Bettany fell in love while filming this movie and later married.
Throw It In: Nash's rambling about different kinds of tea came from the man himself during one of Russell Crowe and Ron Howard's conversations with him. As they left, Crowe said to Howard "I'm using the tea shit."