Holy crossover, Batman! In this week’s episode of Arrow, the “Elseworlds” crossover continued in part two of the three-night event miniseries. And in a major step for the Arrowverse, The CW’s “Trinity” of Oliver (Stephen Amell), Barry (Grant Gustin), and Kara (Melissa Benoist) travel to Gotham City, a city brimming with Batman Easter eggs.

Below, we run down some of the biggest (and smallest) Batman-related Easter eggs, because Batman now officially exists in the Arrowverse.

13. Batman Is a Myth

Jealous much, Ollie? At the beginning of the episode, Oliver disputes the existence of Batman, claiming it’s a boogeyman created by Gotham City to scare criminals. Kara and Barry, knowing full well that Ollie is just jealous someone else is doing the grumpy vigilante thing, laugh at him.

“I’m the original vigilante, Barry!” Ollie tells Barry.

The idea that Batman is a myth recalls a moment early on in The Dark Knight (2008), when a street criminal tells another that they have a better shot at winning the lottery than “running into him.”

Batman Arrowverse Elseworlds
IF you can't hear the Danny Elfman theme, you're looking at this wrong.

12. The Bat-Signal

This one’s hard to miss. When the three arrive in Gotham City, the heroes discover Commissioner Gordon’s Bat-signal on the roof of GCPD, which is just an unmistakable piece of comic book iconography.

11. Vesper Fairchild

In Gotham, the heroes hope to rely on an unseen character named Vesper Fairchild, a Gotham City media personality “who knows everyone” in town. Oliver admits to having a brief affair with Vesper to throw her off from reporting on corrupt business practices conducted by Queen Consolidated.

Introduced in Batman #540, Vesper is indeed a Batman character and did, in fact, have a romantic fling with Bruce Wayne. She was killed by David Cain, a hired gun for Ra’s Al Ghul and father to Cassandra Cain, who is one of many people to hold the mantle of Batgirl.

Christopher Nolan Batman The Dark Knight Arrowverse
Christopher Nolan, on the set of 'The Dark Knight.'

10. “Nolan and Burton”

When the three heroes encounter a random street gang and a squad of Gotham City police officers, an officer radioes HQ asking for back-up “at Nolan and Burton.” This is a very obvious reference to Christopher Nolan and Tim Burton, two filmmakers whose cinematic interpretations of Batman have profoundly shaped popular culture, including even the Arrowverse franchise.

9. Welcome to Chicago

Behind the scenes, production of Arrow briefly moved to Chicago for the “Elseworlds” crossover. Christopher Nolan favored Chicago as his locale for Gotham City in Batman Begins and The Dark Knight. Arrow even used the Chicago Board of Trade Building as its Wayne Enterprises, which Nolan also used as Wayne Tower for Batman Begins.

8. Have You Seen Bruce Wayne?

In “Elseworlds,” Batman/Bruce Wayne has been missing for three years. While Batman could be on a very long mission at who knows where, for everyone else, Batman might as well be dead.

In the comics, Batman has taken long sabbaticals. These include being dead (Final Crisis) or straight up abandoning the mantle (Frank Miller’s The Dark Knight Returns). The Arrowverse didn’t explain the true nature of Batman’s disappearance, but who needs Batman when there’s Batwoman?

Arrowverse Batwoman Ruby Rose
Welcome to Gotham City.

7. Kate Kane, Batwoman

OK, this is hardly an “Easter egg,” but Bruce Wayne’s cousin, Kate Kane (played by Ruby Rose) makes her Arrowverse debut in Part 2 of “Elseworlds.” Fully formed as the vigilante Batwoman, Kate Kane posts bail for our heroes before telling them to scram — Gotham City is her town.

6. No Thanks, Lucius

When Kate Kane offers to have Bruce Wayne’s R&D guy run facial recognition on a sketch, Oliver stubbornly declines. His, and our, loss. Had Oliver accepted, we could have met Lucius Fox, the genius behind Batman’s tech and gadgets who apparently stayed behind in the crumbling Wayne Tower.

Non-comic book readers will know Lucius as the character played by Morgan Freeman in Nolan’s Batman trilogy.

5. The Password Is “Alfred”

We don’t need to over-explain this one, but how weird is it that the wi-fi password of Wayne Tower is “Alfred”?

4. “Frenemies” with Bruce

Apparently Superman has been hopping worlds. Kara tells Kate that her own cousin, Superman, is also “frenemies” with Bruce/Batman, a clever reference to Superman and Batman’s historic and complicated friendship. You don’t get a movie titled Batman v Superman if they’re BFFs.

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From 'Arrow' (2018).
Batman Shakespeare
From 'Batman' (1966).

3. The Bard Himself

In Bruce Wayne’s office, Kara plays with a bronze bust of William Shakespeare. This is a callback to the 1966 Batman series, in which Adam West’s Bruce hid the only access to the Batcave below stately Wayne Manor.

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Hey, why aren't you guys on FOX?

2. Inmates of the Asylum

That part of the episode takes place in Arkham Asylum is one thing. That we get to see some of its patients is something else. As Oliver and Diggle traverse through Arkham’s hallways, they encounter the doors to several notorious Gotham City villains, including:

  • “Cobblepot, O.” (The Penguin)
  • “Isley, P.” (Poison Ivy)
  • “Karlo, B.” (Clayface)
  • “Nigma, E.” (The Riddler)
  • “Guggenheim, M.” (former Arrow showrunner and “Elseworlds” producer Marc Guggenheim)
Arrowverse Mr Freeze Gun
Thankfully Nora doesn't say any cold puns.

Additional moments in Arkham Asylum also tease Mr. Freeze and his beloved Nora (in a cameo appearance played by Cassandra Jean Amell, actress and wife of series star Stephen Amell). A fear toxin belonging to “J. Crane” (Scarecrow) is also unleashed, briefly messing up the minds of both Barry and Oliver and compelling them to fight each other.

Psycho Pirate Arrowverse DC
This guy's psycho.

One minor Batman villain who gets rather substantial screen time is the Psycho-Pirate, who wears his signature gold mask during a failed escape attempt thwarted by Batwoman in her epic first appearance.

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The most powerful handshake in the universe.

1. World’s Finest

When Batwoman and Supergirl say farewell, Kate mentions they are the “World’s Finest.” Besides the fact this was the title of the first Supergirl/The Flash crossover from 2016, the name is also borrowed from the classic World’s Finest series that starred Batman and Superman in a variety of adventures.

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Photos via The CW, Warner Bros.