* ActingForTwo: 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; Creator/CarlaGugino plays Gabe's loving wife and Yulaw's rather trampy-looking consort. [[spoiler: She also plays his wife's BackupTwin in another universe.]]
* HeyItsThatGuy:
** [[NUMB3RS Agent Colby]] swaps jurisdictions and plays a cop in our universe. (He's still in Los Angeles, though.)
** [[Series/SpaceAboveAndBeyond Commodore van Ross]] is tired of the war with the Chigs and becomes an interdimensional prison warden.
** Also, [[Series/SpaceAboveAndBeyond Lt. Col. T.C. McQueen]] has given up piloting and decides to become either an LAPD cop or a criminal.
* WhatCouldHaveBeen: Originally, the film was supposed to star [[DwayneJohnson The Rock]] as the main character, but he chose to do ''TheScorpionKing'' instead. Imagine two doubles giving each other the "eyebrow".
** JackieChan was approached for the project but turned it down because of his policy of never playing the bad guy.