7. Nina Myers Was Originally Supposed To Die In Season 1
It's tough to believe now, but according to Kiefer Sutherland himself, Nina Myers' character was originally supposed to be killed off when Jack shoots her mid-way through the first season. In fact, the scene had already been filmed before the decision was made that Nina would be the mole and as such she would survive the shooting. It led to arguably the show's best plot twist and Jack's most fierce enemy, so it was certainly a great creative decision.