Trivia about Justice League: Crisis on Two Earths.
- Originally titled "Justice League: Worlds Collide," Dwayne McDuffie's script was commissioned for a planned direct-to-video feature in 2004 meant to bridge seasons two and three of Justice League. However, due to a tight TV schedule and various other problems, it was not produced then.
- Despite a heavy rewrite, Justice League: Crisis on Two Earths still contains some elements that bridge the gap between the series finale of Justice League and the revamping of the show:
- The Justice League has six core members, as it was after Hawkgirl leaving in Justice League: Starcrossed: Part III
- The League is assembling new Watchtower following the destruction of the original in Justice League: Starcrossed: Part II
- They have also just finished building and testing the Teleporter.
- Wonder Woman addresses Batman by his real name. The League's secret identities were revealed to each other in "Starcrossed: Part II".
- Wonder Woman keeps Owlman's jet, which gets stuck in "chameleon mode". It is almost identical in appearance to the Invisible Jet she used in "Justice League Unlimited".
- Batman explains to Superman how they are "understaffed." He brings in Aquaman, Black Canary, Red Tornado, Black Lightning and Firestorm to fight Superwoman and company aboard the Watchtower and keeps them around to start expanding the League.
- Flash very clearly appears to be Wally West, specifically based upon the DCAU version; his character model and facial expressions are very similar, despite the different styles.
- Green Lantern mentions that Flash has a car, which appeared in the second season of Justice League.
- The only indications that this is not a bridge between Justice League and Justice League Unlimited are J'onn J'onzz's costume being significantly different, and Green Lantern being Hal Jordan, rather than John Stewart.
- In the behind the scenes featurette, voice director Andrea Romano reveals that James Woods recorded all of his lines as Owlman via satellite from a studio in Connecticut.
- Besides the main antagonists, other Crime Syndicate members who never encountered their alter egos or weren't referred to by name included: Angelique (the alter ego of Hawkgirl), Black Power (the alter ego of Black Lightning), Model Citizen (the alter ego of Looker), Breakdance (Vibe), Sai (Katana) Aurora (Halo), Extruded Man (Elongated Man), Vamp (Vixen), Fortuneteller (Gypsy) Captain Super (Captain Marvel), Uncle Super (Uncle Marvel); Manhawk (Hawkman), Mr. Horrific (Mr. Terrific), Mary Mayhem (Mary Marvel), Megamorpho (Metamorpho), She-Bat (a hybrid of Man-Bat and Catwoman), Warwolf (Lobo), Scream Queen (Black Canary), Archer (Green Arrow), Olympia (Wonder Girl), and alter egos of Wildcat, Sandman, Power Girl, Doctor Fate, Zatanna, Firestorm, Red Tornado, Blue Beetle, Cyborg, and Swamp Thing.