WARNING: The following contains major spoilers for Justice League vs. the Fatal Five.
Bruce Timm has been one of the chief architects in the stable of Warner Bros. Animation since the '90s. Famous for helping spearhead Batman: The Animated Series, Superman: The Animated Series and, of course, the Justice League cartoon in the 2000s, fans often refer to this classic era as the "Timm-Verse."
When Justice League vs. the Fatal Five was announced, eager fans rejoiced because this seemed to be an extension of another Timm-driven project, Justice League Unlimited. However, despite the same character design and animation style, they're not connected.
You can't fault folks for thinking that because, apart from the look, the Holy Trinity of the Justice League are voiced by the same actors: Kevin Conroy is Batman, Susan Eisenberg is Wonder Woman and George Newbern is Superman. Gotham and Metropolis also look ripped from the series, not to mention the same designs are used for villains like Two-Face.
With Jessica Cruz, Miss Martian and Star Boy as the new generation here, we were under the impression this movie continued in the wake of JLU. However, when we dissect the two timelines and how the League interacts with the Legion of Super-Heroes, we see this isn't the case at all.
In the Season 3 episode of JLU, "Far From Home," John Stewart, Green Arrow and Supergirl went to the 30th century to help the Legion fight the Fatal Five. Eventually, they stopped the villains from brainwashing other Legionnaires and, as a result, the universe was saved. However, Supergirl remained behind after falling in love with Brainiac-5, as she finally felt like she was back home on Argo, where she grew up. Green Arrow and John returned to the present to reveal the details of Kara and the Legion.
However, in this flick, when the Fatal Five return to the past to break Emerald Empress out, the League have no idea who they are. Superman, Batman and everyone else are dumbfounded, and also, when Star Boy comes back, he's treated like a madman and institutionalized. Either John and Arrow told everyone and they forgot, or it's just a totally different reality.
What reinforces this is that, in the 31st century when we see the Legion taking on the Fatal Five, Supergirl is nowhere in sight and Brainiac-5 looks different to the JLU version. That means Kara never came here and no link was established with the League. That's why Jessica has no clue about Star Boy, which led to her, Batman and Miss Martian mind probing him for the truth about the future.
In the final scene, when see the Legion comes to Earth for Star Boy's funeral and meets the League for the first time, it confirms this adventure is way disconnected from the Timm-Verse continuity. It's a missed opportunity, as it would have fit into continuity for Supergirl and Brainiac-5 to have sent Star Boy back, which would have perfectly explained why he wasn't in the JLU episode.
Such a narrative would also have bookended John's story nicely by showing Jessica learned from her senior Lantern about the Legion being the police force of tomorrow. Nonetheless, just like the comics, we can chalk this up as an Elseworlds story inspired by this particular universe simply meant to evoke a bit of nostalgia.
Directed by Sam Liu, with a script by Eric Carrasco, Jim Krieg and Alan Burnett based on an original story by Carrasco, Justice League vs. the Fatal Five stars George Newbern, Kevin Conroy, Susan Eisenberg, Elyes Gabel, Diane Guerrero, Daniela Bobadilla, Kevin Michael Richardson, Noel Fisher, Tara Strong, Peter Jessop, Matthew Yang, Sumalee Montano, Philip Anthony Rodriguez, and Tom Kenny. The movie will is now available digitally and will be available on 4K Ultra HD, Blu-ray and DVD release from April 16.