The Man of Steel
In addition to the introduction of Batwoman, “Elseworlds” also featured the return of Tyler Hoechlin’s Superman, and there was no shortage of callbacks to his comic book and movie history. The debut of the evil, black-suited Superman (who actually turned out to be Deegan) is the most obvious, but you also have the revelation that Lois and Clark are expecting a child. In current DC continuity, the pair has a son named Jonathan Kent, who Clark dubbed the new Superboy early on in the Rebirth era.
The Christopher Reeve Superman gets plenty of love, too. When Clark first rips open his shirt to reveal the iconic emblem underneath, you get a small taste of John Williams’ memorable score from Superman: The Movie. Then, when Cisco asks who he is, Clark says, “A friend,” much like Reeve’s Man of Steel did in the 1978 film. Finally, in Part Three, Clark presses a piece of coal into a diamond he can use to propose to Lois, which is what the character did for Lana Lang in Superman III.
Speaking of Part Three of “Elseworlds,” that’s where we finally get to see some of Supergirl’s supporting cast (it is the Supergirl portion of the crossover, after all). Of note, when we’re introduced to the evil version of James Olsen, he refers to himself as “Superman’s Worst Pal.” This, of course, is the inverse of his moniker in the comics, Superman’s Pal Jimmy Olsen, which was also an ongoing series.
The Greater Arrowverse
For fans of DC comic books and movies, many of the aforementioned Easter eggs probably didn’t go unnoticed. However, we’d be remiss if we didn’t touch upon those related to the Arrowverse itself.
Diggle vomiting after moving at super speed has become a running gag (no pun intended), and among the names on the Arkham Asylum doors is Guggenheim, M., which viewers may have guessed is a lighthearted jab at former Arrow showrunner Marc Guggenheim.
There’s also some clever breaking of the fourth wall, such as when Ralph says “it’s not even Tuesday” (The Flash took Supergirl’s Sunday night slot on The CW’s lineup and vice versa) and when Barry says “this has gotta be the craziest thing you've heard in the past three hours” in Part Three (aka hour three) of the crossover.
It’s also worth noting that Part One introduces the longtime Justice League villain Amazo, who escapes from Ivo Labs… except we’ve already seen Amazo and Ivo in the Arrowverse. In Season 2 of Arrow, Dr. Anthony Ivo (the creator of Amazo in the comics) took his ship (which was also named Amazo) to Lian Yu to hunt down the powerful Mirakuru serum. Coincidentally, it’s a nano-adaptive hybrid of Mirakuru that gives this new Amazo its ability to steal metahuman powers.
Last but not least, there’s the long-running fan theory that John Diggle is actually John Stewart of the Green Lantern Corps. While it’s nothing more than a fan theory (at least as far as we know), the writers still give it a shout-out when the Earth-90 Flash sees Diggle and asks him where his ring is.
Could this be a sign of things to come? Probably not, but with Crisis on Infinite Earths coming to the Arrowverse next year, it stands to reason that nothing is completely off the table.
The Flash returns from its winter hiatus on Tuesday, January 15, with Supergirl coming back on Sunday, January 20 and Arrow on Monday, January 21.