Trivia: The One
- Acting for Two: Several actors play counterpart characters from the different dimensions; Jet Li plays both protagonist and antagonist, plus a few additional ones that we see getting killed off. Each character is significantly different from the other; Carla Gugino plays Gabe's loving wife and Yulaw's rather trampy-looking consort. She also plays his wife's Backup Twin in another universe.
- Fake American: This film was early in Statham's career, so this was the first time the Englishman had been called upon to be an American. His accent is better in future films.
- Hey, It's That Guy!:
- Agent Colby swaps jurisdictions and plays a cop in our universe. (He's still in Los Angeles, though.)
- Commodore van Ross is tired of the war with the Chigs and becomes an interdimensional prison warden.
- Also, Lt. Col. T.C. McQueen has given up piloting and decides to become either an LAPD cop or a criminal.
- What Could Have Been: Originally, the film was supposed to star The Rock as the main character, but he chose to do The Scorpion King instead. Imagine two doubles giving each other the "eyebrow".
- Jackie Chan was approached for the project but turned it down because of his policy of never playing the bad guy.