The Arrowverse is huge! The universe started with the TV series Arrow, and since then, it has spawned a number of spin-offs and crossovers. As of now, the mainstream Arrowverse (excluding Supergirl and The Flash (1990), because they take place on separate Earths), consists of Arrow, The Flash (2014), Blood Rush (a live-action web series), Vixen (the animated web series), Constantine, and Legends Of Tomorrow. But what if I told you (not a reference to The Matrix) that it's possible that the cult classic films in the Dark Knight trilogy and the not-so classic film Green Lantern could all be apart of the Arrowverse?
Let's start from the top: When Arrow Seasons 1 and 2 aired on TV, many people drew comparisons between the show and Christopher Nolan's Dark Knight trilogy. I also believe that when one of the producers of the series (probably Greg Berlanti, Andrew Kreisberg, or Marc Guggenheim) was told this, they said the show did draw a little inspiration from the movies, and this is clearly noticeable. The first two seasons of the show are very dark in tone, and realistic, just like the three Batman movies.
Batman Exists In The Arrowverse
We know that Batman exists in the Arrowverse (more on that right here, if you're interested: The 10 Biggest Characters You Didn't Know Existed Within The Arrowverse!). There was the newspaper from the future that said, "Wayne Tech/Queen Inc. Merger Complete," the Oracle reference ("but that was already taken"), the appearances of Harley Quinn and the Calculator, who both could have easy ties to Gotham City), the many references and even appearances of Blüdhaven and Rip Hunter, who has said that he has "seen men of steel die and dark knights fall." All of this is pretty much confirmation that Batman exists in the Arrowverse, but could this version be Christopher Nolan's?
I say "Christopher Nolan's" and not "Christian Bale's" because, well, I don't think Christian Bale, or Bruce Wayne, is Batman after the events of The Dark Knight Rises. The ending of that movie has John "Robin" Blake quitting the Gotham City Police Department, and finding the Batcave, implying that he became the new "protector" of Gotham City. While it's still up for debate whether or not he became the new Batman, Nightwing, or even Robin, we know he probably became someone.
Oracle Also Exists In The Arrowverse
And now I'll try to explain the Oracle reference. In the Dark Knight trilogy, James Gordon was married to Barbara Gordon, had a son named James Gordon Jr., and an unnamed daughter who can be assumed to be Barbara Gordon as well. In TDKR it is revealed that Barbara divorced James, and took the children and left for Cleveland. When they got a little older, or because Barbara might've wanted to, they could have gone back to Gotham. There the daughter or son could have grown a little older and took on the name Oracle, and worked with their father and John Blake (Joseph Gordon-Levitt), the protector of Gotham.
Okay, let's try this: say Batman Begins takes place in the year it came out: 2005. The Dark Knight takes place a year later, so that would put it in 2006. TDKR, takes place eight years after the previous film, so that would put it in 2014. If the daughter, Barbara Gordon, is 8-years-old in TDK (because her age is unspecified, as is her brother's), that would make her 16 in the events of TDKR. Maybe she decides to live with her father or to just live in Gotham City, so she moves from Cleveland to Gotham. Two years later, Oliver Queen (Green Arrow) tells Felicity Smoak he wants to call her Oracle instead of Overwatch, but that name was already taken. What if Barbara Gordon is the vigilante/superhero Oracle right now in Gotham City, and is working with John Blake and James Gordon to protect their city, at the age of 18?
Another thing, but when Ra's al Ghul appeared on Arrow, the producers of the show and even Liam Neeson himself wanted to reprise the role again, but he couldn't due to all of the things he was already filming. What I believe, though, is that before Ra's ever met Oliver Queen, he trained Bruce Wayne to become Batman, which are the events of Batman Begins.
OK, But How Is Green Lantern Involved?
All right, finally the Green Lantern part. I know Green Lantern is hated by many people and is seen as a disaster, mainly for its convoluted plot and horrible CG suit. But — and I know I'll get backlash for this — I think the movie is actually enjoyable. It's definitely not the best DC Comics movie, but I really don't think it's the worst either. I think Ryan Reynolds is actually a great Hal Jordan, and seeing him and other great actors like Mark Strong as Sinestro, Temuera Morrison as Abin Sur, and Michael Clarke Duncan as Kilowog, is awesome. Okay, this kind of turned into a review, but here we go.
In The Flash Season 1 episode "Rogue Air," Hal Jordan is referenced when it is mentioned that a Ferris Air Testing Facility was shut down because of a missing test pilot. Well, that would mean that Hal Jordan was selected as a Green Lantern in 2015. So, if Green Lantern is a part of the Arrowverse, it would have to take place in 2015.
There are maybe two things that might make GL unable to connect. The first is that when a test pilot goes missing, the Ferris Air Testing Facility in Central City was shut down. But in GL there isn't anything that shut down that we know of. What I'm guessing is that when Hal Jordan went missing, all Ferris Air Facilities were shut down except for the one in Coast City where it originated. It's really the only way to explain it.
The other thing through which they don't connect is Amanda Waller. While she was portrayed by a different actress in GL (Angela Bassett), that can be ignored. In the movie, she is shown as a member of the DEO (which has a big presence in Supergirl). But in Arrow, she is the leader of A.R.G.U.S., who created the Suicide Squad. The way I would explain it is that she works for both A.R.G.U.S. and the DEO.
Hal Jordan might have actually appeared in Season 4 of Arrow in a cameo role. In flashbacks when Oliver Queen and Amanda Waller were talking in a bar in Coast City, a guy passes by the camera and he is seen to be wearing a jacket that has the name "Jordan" on it. And this type of jacket is often seen with pilots wearing it. So, Hal Jordan does exist in the Arrowverse, even if it isn't the movie version.
There you have it. My big grand theory. I'm just kidding, I'm sure other people thought of this before me, but I still believe it. Also, think about it, if these four movies are part of the Arrowverse, then that means characters like Batman, Green Lantern, the Joker, Sinestro, Two-Face, Scarecrow, Kilowog, Tomar-Re, Bane, and Abin Sur all exist alongside the Flash, Green Arrow, ATOM, Merlyn, Zoom, and many others.
So, I do have this all in order, in case you're wondering or need to know: Batman Begins, The Dark Knight, Arrow (Season 1), The Dark Knight Rises, Arrow (Season 2), The Flash (Season 1), Arrow (Season 3), Green Lantern, Constantine (Season 1), and then it continues with the normal Arrowverse from then on.