Batman v. Superman: Dawn of Justice took the well-known superhero characters into a territory never seen before on the big screen: a one-on-one battle. Given Batman and Superman's deep historical lore in their respective comic books, their extensive film universe, and the directorial history of filmmaker Zack Synder, the movie undoubtedly contains a number of Easter eggs and secrets for eagle-eyed fans to spot. Here are the 12 best.

01 of 12 Omega In perhaps the most notable dream sequence in the film, we see a dark future where Superman (Henry Cavill) has conquered the world. Batman (Ben Affleck) still fights the good fight, though, dressed in an outfit that we see Batman's son, Damian Wayne, wear in another possible future in an issue of Grant Morrison's Batman run (also a dark future). Throughout the film, there are a number of references to the villain Darkseid, who will most likely be the villain in the upcoming Justice League film. One is the presence of a Mother Box in the video on the creation of Cyborg (which we see along with Wonder Woman as she learns of the existence of future Justice League members Aquaman, Flash, and Cyborg). That might not count as an Easter Egg since it is so prominently featured, but this carved Omega symbol is just subtle enough to count. Omega is the final letter of the Greek alphabet and has become Darkseid's logo over the years. Darkseid even fires powerful "Omega beams" from his eyes, including once in a famous fight between Darkseid and Batman.

02 of 12 Joker Card on Batman's Gun Ahead of the Joker appearing in the upcoming DC film, Suicide Squad, the Joker gets a lot of small references within this film. One of the most obscure also happens in the aforementioned dream sequence, where you can just make out that Batman has a Joker playing card attached to his gun. There's also a scene where we see a memorial with Robin's costume in it that has written on it, "Ha Ha Joke's on you, Batman." The film pauses on the suit long enough for you to read the writing, so it's not really an Easter Egg. It's just a flat out reference to the fact that Joker likely killed one of Batman's Robins in this film universe.

03 of 12 Joker Graffiti During Batman and Superman's battle in an abandoned building towards the end of the film, there is a ton of graffiti on pillars throughout the building. Some people insist that there is graffiti that says "Who Watches the Watchmen?" There definitely is a reference to Batman's villain, the Riddler, with question marks abounding, and the above sly Joker reference: "Joe ----> KR".

04 of 12 Gotham City Cops Pay Tribute to Two Great Batman Creators Early in the film, in an homage to a similar sequence early in Frank Miller's Dark Knight Returns, we see two Gotham City police officers, a rookie and a veteran. It is not until the end of the film that we learn the names of the two officers: Rucka and Mazzucchelli. This, of course, is a reference to two great Batman comic book creators. Greg Rucka wrote Detective Comics for three years from #742-775, as well as co-writing (with Ed Brubaker) Gotham Central, an acclaimed series that spotlighted the members of the Gotham City police department. David Mazzucchelli was the artist with writer Frank Miller on the legendary storyline, Batman: Year One, cementing his status as one of the greatest Batman artists of all-time.

05 of 12 It's Not 1938! Clark Kent and his editor at the Daily Planet, Perry White (Laurence Fishburne), have a lot of disagreements over Clark's reporting. Clark and Perry's biggest area of disagreement is over Clark's obsession with Batman and what Clark feels is his violation of basic justice. Perry keeps trying to get Clark to do sports stories while Clark wants to be a crusader. They argue and Clark states, "When the Planet was founded, it stood for something, Perry." Perry shouts back, "So could you if it were 1938!" 1938, of course, was when Superman was first introduced in the pages of Action Comics #1.

06 of 12 Action Comics #1 Cover Speaking of Action Comics #1, the image of Superman lifting up a car is featured in the film on the pin-up board by Wallace Keene's desk. Keene (Scoot McNairy) was a Wayne employee whose family lost their lives in the attack on Metropolis in Man of Steel (Keene lost the use of his legs due to injuries sustained in the same attack). Keene is obsessed with Superman and the pin-up board on top of his desk in his small apartment is filled with newspaper clippings about Superman, plus a photo/drawing that is a direct homage to the Action Comics #1 cover.

07 of 12 Metropolis Memorial Pays Tribute to BvS Crew Members We first meet Keene right before he vandalizes the memorial to the victims of the Attack on Metropolis. We see him first visit the memorial and we see a bunch of names on the wall of the memorial. The names are all people who worked on Batman v Superman: Dawn of Justice in one capacity or another. The cited crew members include visual effects assistant Katie Barker, costume production assistant Richard Gartrell, costumer Annie Jewell, specialty costumer Tony Acosta Jr., and key textile artist Ivory Stanton.

08 of 12 Ralli's Diner One of the most memorable stories during John Byrne's run as the writer and artist on Superman's series was a back-up story in Superman (Vol.2) #9, which starred Lex Luthor, who Byrne had re-invented as a wealthy businessman who is seen as a legitimate businessman by the rest of the world (part of his hatred for Superman is the fact that, before Superman came around, he was the closest thing people had to a hero in Metropolis). In the story, Luthor propositions a young married waitress, asking her to spend one month of her life with him in exchange for one million dollars. He goes to his car and tells her that she has ten minutes to decide before he leaves. She frets over the decision and seemingly has finally come to a decision, but Luthor has already left. His little game is always to leave right before they officially make up their mind, as he figures the uncertainty of whether she would have taken the money will drive her nuts. Luthor is one messed up dude. In any event, in Batman v Superman: Dawn of Justice, Superman's mother, Martha Kent (Diane Lane) works at Ralli's diner.

09 of 12 300 Reference Zack Snyder likes to reference his past films. He referenced his first big hit movie, 300, in both Watchmen and Man of Steel and nowhere, as well, during a sequence where Superman saves a rocket with 003 on it. That follows closely with how he homaged the 300 in Watchmen, where Comedian's apartment number is 3001 (the 300 references in Man of Steel is that the local Smallville football team is the Smallville Spartans, like the Spartans in 300). Snyder also pays homage to Watchmen by having three of the actors from the film play roles in Batman v Superman: Dawn of Justice. Jeffrey Dean Morgan (The Comedian in Watchmen) plays Thomas Wayne, Carla Gugino (the original Silk Spectre in Watchmen) plays the voice of the Kryptonian ship and Patrick Wilson (the second Nite Owl in Watchmen) plays the voice of the President of the United States.

10 of 12 Dark Knight Returns Cover Redone A cool Easter Egg that movies sometimes do is to put in a visual reference to a classic comic book drawing during the film itself. Sam Raimi's Spider-Man 2 put in a visual recreation of "Spider-Man No More!" while Bryan Singer's Superman Returns recreated the aforementioned cover of Action Comics #1. In Batman v Superman: Dark of Justice, Zack Snyder was heavily influenced by Frank Miller's Dark Knight Returns, so he threw in a visual recreation of the legendary cover to the first issue of The Dark Knight Returns.

11 of 12 Stormtrooper Reference At the end of the film, Lex Luthor (Jesse Eisenberg) is arrested. His prisoner number? TK-421. That's the call sign of the Stormtrooper that Luke Skywalker knocks out and takes the uniform off in the original Star Wars. Zack Snyder is a big Star Wars fan, but even with that in mind, it's certainly a surprisingly obscure reference to make.