Shared with you
The only film in the trilogy where no one on the Ducks team is even referred to as the team captain. Banks is (mistakenly) referred to as captain in the second film, until Charlie later is. And Charlie is correctly called the team captain in the third film. (Before being stripped of it and then later, being awarded it again.)
Jake Gyllenhaal, who was unknown at the time, auditioned for the role of Charlie Conway, but his parents wouldn't let him do the movie so the producers ended up casting Joshua Jackson.
Before Emilio Estevez was offered and accepted the role of Gordon Bombay, Charlie Sheen, his brother, was offered the role, but turned it down.
Leonardo DiCaprio auditioned for the part of Charlie Conway but lost out to Joshua Jackson. In similar fashion, Juliette Lewis tried out for the part of Connie, but lost out to Marguerite Moreau.
The original premise of Mighty Ducks was much darker with very little comedy about an ex-NHL player turned alcoholic who seeks revenge on his old coach by coaching opposite him. The main idea stayed when Disney bought the rights to the movie, but some elements were changed (such as Bombay is now a lawyer, who never played in the NHL, who must do community service for a DUI), including much more emphasis on comedy and downplaying most of the adult themes.
Vincent LaRusso wasn't given the role of Adam Banks initially, but later it was given to him when the child who originally played Banks became too difficult to work with.
Basil McRae, Michael Modano: of the Minnesota North Stars (now Dallas Stars) appear, playing themselves.