- Ability over Appearance: Anna was written to be American, but Alice Braga was the only person producers wanted for the role.
- Defictionalization: At one point there is a billboard for a Superman/Batman crossover film. Fast forward to 2016, and Batman v Superman: Dawn of Justice has been released, and Creator/WillSmith became a part of that cinematic universe.
- Executive Meddling: Like you wouldn't believe, which resulted in the generic 'kill-them-all' Heroic Sacrifice theatrical ending. The ending was focused grouped to hell and back again and resulted in most of the foreshadowing regarding the intelligence of the Darkseekers and the fact that Neville's current test subject is the mate of the Alpha Darkseeker who just wants her returned to the pack completely pointless and made the ending seem rushed and confused. Thankfully the original ending was included in the DVD bonus features.
- Real-Life Relative: Will Smith's daughter, Willow Smith, plays his daughter in the movie.
- Saved from Development Hell: Ridley Scott planned an adaptation in 1998 starring Arnold Schwarzenegger. The studio's art direction and special effects workers had even begun working on a design for the apocalyptic mutant creatures. However, some high-profile big-budget failures for Warner Bros., and the huge (for that time) initial budget of 125 million dollars, led to the project being put into turnaround. If the film had been made from Mark Protosevich's original screenplay, it would have differed from the final version in three major ways: it was to be set in the Bay Area of California, it would have been more of an action film, and less of a drama, and it would have been filmed with the intent of being R-rated, which would have possibly drawn in fewer viewers.
- Stillborn Franchise: There were plans for a prequel, but the film-makers could never find a story that worked. Some of the ideas that were bandied about include a road picture prequel, taking place on a trip to Washington D.C., that would have involved a zombie elephant, and an outbreak during the Macy's Thanksgiving Day parade. They also considered a straight up sequel, with Will Smith playing the clone of his character from the first film.
- Uncredited Role: Emma Thompson has an uncredited role as Dr. Alice Krippin, who appears on television explaining her vaccine for cancer that mutates into the virus.
- What Could Have Been:
- Tom Cruise, Nicolas Cage, Michael Douglas, Mel Gibson, Daniel Day-Lewis, and Ted Levine were considered to star over the years the film was in development. Kurt Russell was once considered to star in the late 1990s, but after the failure of Soldier, he was no longer considered.
- Will Smith wanted Guillermo del Toro to direct, but he was busy with Hellboy II: The Golden Army.
- In 1999, in an early point in development, Tim Burton was interested in the project.
- Michael Bay was set to direct at one stage, but he and Smith did Bad Boys II instead.
- Writing by the Seat of Your Pants: The film was green-lit without a script.
Trivia / I Am Legend