Ever since director Zack Snyder's Man of Steel, the DC Extended Universe of movies has been growing and growing. From the introduction of Batman in Gotham City to a flashback to the days of the first Great War, from an enchanted invasion of Midway City to the imminent formation of the Justice League, we have gotten more and more movies that work to establish this universe as one that is richly and deeply rooted in its own history and reality. Each new movie brought with it new characters, new details and new elements whose goals were to expand the mythology of the DC movie universe.

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While many story beats built off one another -- like Superman's evolution from superhero to reviled public figure and Batman's lonesome brute finally finding hope, or Wonder Woman's never-ending need to save mankind, no matter the era -- there have been many plot points that were set and followed up on nicely. However, with the universe growing at an exponential rate, with so many things happening from one movie to the next, there are certain elements that were easy to miss completely. Today, CBR lists 15 DCEU plot points that you most likely missed or completely forgot about.

15 HARLEY QUINN HELPED KILL ROBIN

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In Batman v. Superman: Dawn of Justice, viewers were given the first hints at the overarching mystery of a deceased Robin. The suit, displayed in the Batcave, was signed by the Joker himself, a spray-painted message that would forever taunt Batman. After taking note of Bruce's state of mind, it was clear that this loss weighed heavily on him.

While everyone assumed that Robin was murdered by the Joker, Suicide Squad would give us a bit more information in the form of Harley Quinn's rap-sheet, which informed us that she was an accomplice to Robin's murder. This means that Joker wasn't alone when he killed Robin -- Harley Quinn is just as guilty, and until we know for certain, we can't be sure which of these two delivered the killing blow.

14 THERE WAS A PREVIOUS DOOMSDAY

This plot point may have been easy to miss. In Batman v. Superman: Dawn of Justice, when Lex Luthor finds himself inside the Kryptonian ship with Zod's body, he is informed by the ship's central intelligence that by following his current course of action, the villain will create an ancient Kryptonian deformity, a “desecration without name” – something that was now forbidden by the council of Krypton.

The ship's voice implies that a creature like Doomsday was already created, a long time ago. This seems to hint at the fact that the Doomsday creature that manages to kill Superman wasn't the first, but simply another. This makes us wonder how many more Doomsdays were created, and what damage they caused that led to them being forbidden. Recently, it has even been hinted that Steppenwolf might have proven his stripes by killing one of them.

13 KRYPTON'S DESTROYED MOON

Man of Steel Krypton moon

Man of Steel kickstarted the DCEU by fully establishing the DC Universe on the big screen, with many layers hinting at a deep and rich history. As we found ourselves on Krypton, viewers could quickly catch a glimpse at one of its shattered moons, a moon that bore the name of Wegthor in the comic books. While this could be considered an Easter egg, it's also a story that hasn't been explored yet.

In fact, in the comics, the Kryptonian responsible for the destruction of Wegthor is Jax-Ur, who does appear in the film as part of General Zod's army. His actions led to him being sentenced to the Phantom Zone and, considering that he got sucked back into his prison at the end of the movie, there is always the chance that he could return to pose a threat to the Earth.

12 WONDER WOMAN WAS LOOKING FOR THE SWORD OF ALEXANDER

BvS-Diana-and-Bruce

When we find Diana Prince in the present day in Batman v. Superman, we see that she's not the hero she once was. In fact, there are ample amounts of secrecy about her. After attending Lex Luthor's party, we next see her at another fancy social event, this one a ball held in a museum. There, Diana is taken directly to the museum's prized possession, the sword of Alexander.

Bruce Wayne tells her that the sword is a fake, but before he can say where the real one is, Diana gives the answer, knowing full well where the sword is. Was this simply a way to show us that the Amazon was very good at her job as a museum curator, or is this hinting at Wonder Woman's need to find the mythical sword? Perhaps she was hunting something very particular, something that needed a legendary weapon to be dealt with.

11 AMANDA WALLER KNOWS BRUCE WAYNE IS BATMAN

Viola Davis as Amanda Waller from Suicide Squad

If you stuck around to watch the Suicide Squad credits, then you know that Bruce Wayne and Amanda Waller met. The secret meeting takes place in a restaurant, where both characters agree to a deal of sorts. While Waller is seeking help for her Task Force X fiasco, Bruce Wayne is after information. Once their business is done, Amanda tells Bruce with aplomb that he “should stop working nights.”

This not-so-subtle jab is Amanda's way of telling one of the world's richest men that she knows exactly what he is up to in Gotham City. Even Bruce knows that there is no point in arguing with her. Instead, he makes her a threat of his own, to stop her Suicide Squad program, or he and his friends will do it for her. This is something that screams “to be continued.”

10 WAYNE ENTERPRISES IS RESPONSIBLE FOR THE SQUAD'S BOMBS

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This is one of those times where you had to be paying attention. In Suicide Squad, the Joker's goal was to find Harley Quinn and free her from Amanda Waller's grasp. But in order to achieve that goal, he had to find a way to deactivate the bomb that Waller had implanted in all Task Force X members. To do so, Joker and his crew made their way to Van Criss Laboratories.

Thanks to the title on the screen, we are informed that Van Criss is “a division of Wayne Corp.” This means that Bruce Wayne's own company is responsible for making the bombs that are implanted in the necks of the Suicide Squad. Now, whether Bruce knows about this or Waller managed to get all this to happen behind his back remains to be seen.

9 BRUCE WAYNE ALREADY MET BARRY ALLEN

flash bvs cameo

The Justice League trailers have already shown us the scene where Barry Allen meets Bruce Wayne, where the latter attempts to recruit the former into his superhero team. But, many forget that Bruce actually met Barry prior to that, in Batman v. Superman. In fact, that meeting occurred right after Bruce had his “Knightmare” dream of a dark future ahead.

When he woke up from his vision, Bruce saw a time-traveling Barry in a swirl of lightning. The speedster gave Bruce a warning of things to come, only for the billionaire to once again wake up, wondering what had just happened. We don't know if Bruce acknowledges that this meeting has in fact happened or not, but chances are we will find out a whole lot more about it in Justice League.

8 KRYPTON VISITED EARTH BEFORE

Man of Steel Supergirl teaser

In Man of Steel, viewers came to learn a whole lot more about Krypton, just as Kal-El did. Thanks to the digital version of Jor-El, we are told of the Kryptonians' ancient history, not just as a people on their planet, but through the stars. In fact, we come to learn that not only did Krypton go about sending many settlers on missions throughout the universe, but one of their ships also found its way on Earth, long ago.

How far did these settlers reach, and what other planets and races did they come across? Did they leave anything else on Earth besides an empty spaceship? Later in the film, Zod would mention that he sought these outposts across the spaceways, but that he only found death there. What happened to these Kryptonians? Why are they all dead? Were they systematically hunted? This is something that needs to be answered.

7 JIMMY OLSEN IS DEAD

jimmy olsen batman v superman

You might not even remember this, but Superman's pal and his most trusted friend outside of the Justice League, famed Daily Planet photographer Jimmy Olsen has appeared in the DCEU – although his presence was an incredibly brief one, as Jimmy didn't make it out of his introductory scene alive. Although he appeared as an unassuming but brave photographer in Batman v. Superman, Jimmy was actually more than that.

In truth, Jimmy was a spy, a CIA agent who used Lois Lane's credentials for cover down in Africa. We don't really know what his mission was, and if he had a previous relationship with Lois Lane before their fateful assignment. If they had worked together before, one can assume that the revelation was quite shocking to Lois, as well as Daily Planet reporter Clark Kent – if he ever met Jimmy, that is.

6 THE PHANTOM ZONE

The Phantom Zone is a frightful reality used by the Council of Krypton to imprison criminals and villains. It is the place where Zod and his army were banished after attempting to take control of Krypton in the opening segments of Man of Steel. While the planet's explosion did manage to free Zod and his followers, surely the same cannot be said for everyone in there.

Considering that, after Zod's betrayal, the Council was quick to sentence the villain to the Phantom Zone, it stands to reason that the prison has been in Krypton's arsenal for a long while. This would indicate that the Council has used the Zone before, and banished many others to its confines. Who else is in there then, and how long have they been imprisoned?

5 THE GOVERNMENT AND LEXCORP KNOW ABOUT THE LEAGUE

Bruce Wayne may have kept his identity a secret from the world, but that isn't the case for every superhero out there. In fact, in the mid-credits scene of Suicide Squad, we saw that Amanda Waller had files on both Barry Allen and Arthur Curry – at least. While Bruce Wayne took possession of those files, it nonetheless means that the government is aware of these metahumans.

Furthermore, we also saw that Lex Luthor also kept detailed files on Barry, Arthur, Victor Stone and Diana Prince. Not only was he keeping track of them, he was aware of all of their superpowers. This means that the identities of the superheroes were not only known to the government, but one of the most powerful businessmen in the world – before most of them ever set out to become superheroes.

4 WONDER WOMAN CAN'T GO HOME AGAIN

Wonder Woman and the Amazons in 2017's Wonder Woman film

While we met Wonder Woman in the present day, working as a museum curator of sorts in Batman v. Superman, her solo movie would show us her origins during the year 1918. Back then, she lived a peaceful life on Themyscira, surrounded by all of her sisters and training to be a fierce warrior. But Steve Trevor's arrival sparked her need to leave her home behind and go stop Ares.

Before Diana leaves by way of the sea, her mother bids her farewell by offering her one final warning: if she leaves Paradise Island, she can never again return. Whether this is a rule of the Amazons or some sort of magic that prevents Diana from finding her home again remains to be seen, but that doesn't change the fact that for the better part of a century, Diana has never been able to return home to her sisters.

3 JOKER AND HARLEY ARE ON THE LOOSE

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Harley Quinn spent the better part of Suicide Squad as a member of Task Force X and a prisoner of Amanda Waller. Although we did see her free in some flashbacks, where she was living a life of royalty and crime alongside the Joker, her present day has been spent in incarceration. However, in order to change things up, the movie ended with Joker breaking Harley out of Waller's prison.

This means that, from that point afterwards, say in movies like Justice League, Joker and Harley Quinn are now on the loose, free to roam the streets of Gotham and unleash chaos. Perhaps they are even aiming to rebuild their criminal empire after Harley has been away. It will therefore be interesting to see what the characters have been up to when they pop up again.

2 DR. POISON IS ALIVE

Doctor Poison dies in the first Wonder Woman film

The Wonder Woman film established Dr. Poison not only as an antagonist of the story, but also as something of a nemesis for Diana Prince. Sure, there is no way that Dr. Poison could hold her own against Diana in battle (unless she decided to take one of her special pills), but the villain was given a lot of depth and correlation with the likes of the Amazon goddess.

Although Wonder Woman battled Ares in a storm of fire and destruction, it's easy to forget that Dr. Poison was also present in the final conflict. In fact, she managed to get out of it alive, after Diana decided to spare her life. This means that Poison is now out there somewhere, possibly up to her old tricks again. We don't know if we will see her again in a sequel, but we sure hope so.

1 LEX LUTHOR HAS ALL THE KNOWLEDGE OF THE UNIVERSE

eisenberg lex luthor

When Lex Luthor broke into Zod's Kryptonian ship with the General's remains in Dawn of Justice, not only did he create Doomsday, but he managed to gain a whole lot of knowledge about the universe. In fact, when Luthor boards the ship, the computer informs him that “The Kryptonian archive contains knowledge from a hundred thousand different worlds.”

This means that, while Superman and Batman were getting ready to fight each other, Lex Luthor was learning about 100,000 planets across the universe. Sure, he learned about Apokolips and Steppenwolf and the Mother Boxes, but what else did he learn about? What other planets are out there, what other civilizations, maybe even superheroes? Surely Luthor knows about the Green Lantern Corps, and what happened to them. Right now, he might be the man with all the cosmic answers.

Do you think any of these will be addressed in future DCEU movies? Let us know in the comments!