- Author's Saving Throw: The museum in the Legion era establishes that Hal does eventually become a Green Lantern, for those who were disappointed that he didn't seem to be one in the DCAU due to parts of his story such as his rogues gallery and backstory being given to John and Kyle.
- Epileptic Trees:
- A lot of fans suspect that this movie is an entry to a revival of the DC Animated Universe. This is mainly because Bruce Timm is leading the project, the style is the same as the DCAU, with the Trinity being reprised by their DCAU voice actors, the current ambiguity of its canon status, Batman and Harley Quinn being considered by the man himself as canon to the franchise, and the entire movie appears as a larger version of a Justice League special. On the other hand, there are those who think that this is merely another Superman: Brainiac Attacks case, where it looks as if it were a DCAU entry due to reuse of voice actors and art style, but actually isn't. The difference is, Brainiac Attacks portrays several characters quite differently even if it looks like a long episode of Superman: The Animated Series. Everyone who was in the DCAU acts like they did there. However, the roster is very different from the DCAU Justice League.
- That the Fatal Five are after Jessica because she's somehow connected to the Emerald Eye of Ekron, considering they're trying to rescue Emerald Empress and there's no other obvious connection between the two parties besides Jessica being a Green Lantern and the Eye belonging to the Green Lantern Corps, not to mention that Emerald Empress offhandedly mentioned in "Far From Home" that Green Lanterns were "a rare sight these days [in the 31st century]" and seemed to be perfectly content with just having John Stewart under her mind control even though Supergirl escaped from it.
- Watchtower Database suggests that due to the timeline, since Jessica survived her attempted murder during the Justice League and Justice League Unlimited Time Skip — where it's possible that a Broad Strokes of Justice League: Crisis on Two Earths happened, she could have gotten her Lantern ring after Power Ring was defeated in that movie.
- Fan-Preferred Couple: Jessica and Thomas.
- Harsher in Hindsight: Batman complains to Miss Martian that he doesn't want to work with teenagers because of their lack of experience. In response, Miss Martian reminds him of Robin (Tim Drake), to which he concedes to. Let us not forget of the guilt he will carry over what will happen to Tim while on duty in the near future...
- Hilarious in Hindsight:
- In Batman and Harley Quinn, Batman tries to contact the League for help, but after he learns that the only available Leaguers are C-list heroes and Booster Gold, he changes his mind because he doesn't want to deal with any of them. Here, he has to work with Miss Martian, Star Boy, and Jessica Cruz, who are all unknown characters to the general public (Miss Martian was relatively obscure until the Young Justice cartoon, Star Boy and the rest of the Legion of Superheroes are very obscure due to lack of coverage in DC television and film, and Jessica is a recent addition to the Green Lanterns and may receive a bump from DC Super Hero Girls, which will be released before the movie).
- In Elena of Avalor, Diane Guerrero played Vestia, the sister of a character named Cruz. Here, she plays a girl named Jessica Cruz. A fellow Elena of Avalor cast member, Myrna Velasco, whose character, Carla, played an ally to Cruz and Vestia, would later be announced to be playing Jessica in the DC Super Hero Girls animated television series.
- Bruce Timm once dressed up as Two-Face when Batman: The Animated Series came out (as shown on the behind-the-scenes documentary on the Blu-Ray release). In this movie, he voices Two Face himself.
- They Wasted a Perfectly Good Character:
- Simon Baz, another Green Lantern and Jessica's partner in the comics, has no presence in Jessica's arc and doesn't even seem to exist according to the display of Green Lantern Leaguers in the Legion museum. In fact, he's the only Green Lantern out of the main six that doesn't appear in the display.
- Supergirl is not seen or brought up, despite her last appearance in the show and the DCAU as a whole being her staying in the 31st century to join the Legion. In-universe, it can be excused as her being on a mission elsewhere, and out-of-universe, to prevent Continuity Lockout.
- Unexpected Character:
- Jessica Cruz making her debut as the movie's only appearing Green Lantern, and has been described as the lead character of the film.
- Miss Martian, especially if this movie is a DCAU entry, as her existence would contradict J'onn being the Last of His Kind if she were a Green Martian or would suddenly introduce the White Martians into the DCAU since their place is taken by the similar Imperium in this continuity.
- Mister Terrific as a main cast member, since he was barely seen performing any heroics due to being the League's Mission Control back in Justice League Unlimited.
- The choice of characters in the movie is interesting, given that Jessica, Miss Martian, and Mister Terrific have no connection to each other or Star Boy or the Legion of Super-Heroes and the Fatal Five anywhere else, although Star Boy and Mister Terrific have interacted in one of the Justice Society of America: Kingdom Come special issues.
- The appearance of Two-Face, Harley, and Ivy as Arkham Asylum inmates in addition to Miss Martian transforming into the second Robin, since the Bat-Embargo restricted any limit or ban the use of Batman-related characters (outside of Batman himself along with his obscure allies and Rogues Gallery) from appearing in the Justice League Unlimited and it was assumed that this would've carried over into the movie in spirit to keep the Batman mythos and Justice League mythos separate.
- Hal Jordan and Guy Gardner appearing via cameo and being confirmed to become Green Lanterns and members of the Justice League in the near future, as there had otherwise been no solid indication that either of them existed as heroes in the DCAU. Hal was a One-Scene Wonder (time was altered, with Hal suddenly replacing John mid-sentence to the confusion of those with Ripple Effect-Proof Memory. Apparently, he's who joins the Justice League if John Stewart never does.) and Guy was pseudo-canon by the Unlimited tie-in comics.
- Win the Crowd:
- Possibly in response to the Twitter hashtag phenomenon #JLReunion (which DC acknowledged), DC is giving Justice League/DCAU fans what they wanted by having Bruce Timm work on another action-oriented Justice League entry along with the return of the Trinity's DCAU voice actors and the introduction of new material including Jessica Cruz and Miss Martian. It should be noted though that Susan Eisenberg has since confirmed that the movie was made and conceived before the hashtag #JLReunion started.
- Jessica's anxiety will be focused on, which has many of her fans who were skeptical of the film very excited, especially since mental illness and other mental issues has an unfortunate streak of being misrepresented in media.
- Batman and Harley Quinn was quite divisive for its poorer animation and emphasis on comedy. Justice League vs. the Fatal Five has animation on par with Justice League: Gods and Monsters and is more heavy on story and character development.
YMMV / Justice League vs. The Fatal Five