In the original ending of the film, Mitch died from his wounds after saving Charly and Caitlin. But it was decided that this would be too much of a Downer Ending and so Mitch survived and became a national hero.
Also, originally the name "Sam Caine" was simply a name her brain threw up as an anagram for "amnesiac". In the finished film it's her former alias.
The 100-year-old Windermere House in Muskoka was a planned filming location, but it burned to the ground before the scenes had been finished.
Studio executives considered rewriting the film to have a male lead, with Steven Seagal or Sylvester Stallone in mind.
The ice skating scene was scripted to have Samantha perform a double axel flip and shoot from under her upside down head. After testing it out on location and with green screen, they dropped it from the film.