Easter Eggs and Things You Might've Missed in "Crisis on Earth-X"

King Shark

The opening montage of "Crisis on Earth-X" was not only the perfect introduction of four teams of characters coming together to celebrate the wedding of their friends, but it was also a great way to tuck in some pretty great Easter eggs. Felicity name-dropped Damien Dahrk (now alive on Legends of Tomorrow) and Supergirl fought a Dominator (the bad guy alien race at the heart of last season's crossover, "Invasion!") but the best Easter egg tucked into that montage belonged to King Shark. The Flash (Grant Gustin) was seen fighting the metahuman as Iris (Candice Patton) contacted him concerned that not everyone had RSVP'd.

However, this Easter egg, while awesome, also made us wonder... how exactly did King Shark end up in Central City? The last time we saw King Shark, he was serving as a "guard shark" of sorts for a Dominator power source in an A.R.G.U.S. facility, and while The Flash and Captain Cold (Wentworth Miller) did break into said facility and steal the power source, King Shark didn't escape.

Lobo

Also included in the RSVP montage, Supergirl fighting the "so last year" Dominator wasn't the only Easter egg in the National City scene.

While the DEO tried to figure out exactly what threat had come to Earth from deep orbit, one of the possible alien types mentioned were Czarnians. This was a sly reference to the DC Comics character Lobo. Lobo is the last Czarnian, just as Superman is the "last" Kryptonian and Martian Manhunter is the "last" Martian, but instead of coming to Earth as a refugee, Lobo isn't a victim of the end of his world. He's the reason for the end of his. The brutal character murdered most of those on his world which would make him potentially a pretty big threat to come flying out of deep orbit.

Lobo has yet to be seen on screen in live-action form, but Supergirl has made a slight reference to him before. A 2016 episode quietly referenced a dangerous interstellar bounty hunter who didn't have a name beyond "him," but was strongly believed to be Lobo.

Spider-Man

On Legends of Tomorrow this season, Stein (Victor Garber) and Jax (Franz Drameh) had been looking at ways to separate themselves so that Stein could retire and go home to his family. Cisco (Carlos Valdes) and Harry (Tom Cavanagh) came up with a serum that would do it, but they would be left powerless. This led Stein to come up with a way to give Jax spider powers.

While this wasn't the first time the Arrowverse has mentioned Spider-Man this season, this reference was more detailed than others. Stein ended up explaining all of the webslinger's powers... and explained to Jax that he would have none of those. Jax ends up not taking the power-giving virus, and who can blame him? Why just have spider powers if you can't be Spider-Man?

Greatest American Hero

Did you recognize the priest at Barry and Iris' wedding? If you were a fan of the 1980s ABC show The Greatest American Hero , you just might have! William Katt, who starred as hero Ralph Hinkley in the superhero comedy-drama that aired on ABC between 1981 and 1983, played the priest at the wedding.

On The Greatest American Hero, Hinkley, who is a substitute teacher in the Los Angeles public schools, encounters aliens while on a field trip who give him a special suit that allows him to have superhuman abilities. The aliens also instruct Hinkley to work with FBI Special Agent Bill Maxwell to fight crime and injustice in the world.

Hinkley's special suit grants him many powers, including flight, super strength, invisibility, super speed, and telekinesis, making him almost a one-man super team. Unfortunately for the wedding priest, however, Katt left that suit and those powers back with the Hinkley character. They would have come in handy as the Nazi's crash the wedding and vaporize the priest before he can finish marrying Barry and Iris.

Mystery Wedding Girl

If you noticed the girl at the wedding who was serving sparkling water and had an extended moment gushing about the wedding with Barry, you may have already considered that she could be Dawn Allen or even Jenni Ognats, Barry's daughter and granddaughter, respectively, from the future.

What you might not have considered, though, is that this wasn't the first time the actress, Jessica Parker Kennedy, has appeared in a DC Comics-related television show. Kennedy appeared as the villain Plastique/Bette Sans Souci on the second episode of Smallville's eighth season back in 2008.

Dayton Optical Systems

During the second hour of the crossover, the Earth-X Nazis broke into a lab so Supergirl (Melissa Benoist,) Green Arrow (Stephen Amell,) and The Flash (Grant Gustin) head there to stop their evil counterparts. While the fight between them doesn't go particularly well, the sign on the building may be familiar to some DC Comics fans: Dayton Optical Systems might just be a sly reference to Doom Patrol character Mento, aka Steve Dayton.

In the Doom Patrol comics, Dayton is one of the world's richest men, and he builds himself a helmet that enhances his mental abilities. Calling himself Mento, Dayton attempts to impress a member of Doom Patrol, Elasti-Girl. His plan works. They pair marry and adopt Beast Boy, but their happiness is short-lived. Elasti-Girl is killed, leading Mento to hunt for her killers, General Zahl and Madame Rouge.

Six Degrees of Victor Garber

You've heard of six degrees of Kevin Bacon, but the Arrowverse has six degrees of Victor Garber. Colin Donnell (Tommy Merlyn-X) posted on Twitter that he and Garber were once in the same musical together in New York. This prompted Christina Brucato to reply that she plays Garber's daughter, Lily Stein, on Legends of Tomorrow as well as Donnell's sister on Chicago Med, making them all some special version of family.

And I play Victor's daughter on @TheCW_Legends and YOUR sister on @NBCChicagoMed... 6 degrees of victor Farber #family

— Christina Brucato (@chrissybrucato) November 28, 2017

'Smallville' again

If you missed that Jessica Parker Kennedy was Plastique on Smallville, you had a second opportunity to catch a Smallville reference. Eobard Thawne (Tom Cavagnah) threatens to kill Felicity Smoak (Emily Bett Rickards) if she doesn't give him the password to turn the power back on at STAR Labs so that he can take out Supergirl's heart. As he threatens her, he tells her that while The Flash, Green Arrow, and others are well known in the future, recounted as part of an "age of heroes," Felicity herself is forgotten by history.

In the Smallville episode "Legion," Chloe Sullivan is taken over by Brainiac, leading members of the Legion of Super-Heroes to want to kill her to eradicate Brainiac once and for all. They justify this by noting that Chloe isn't remembered by history, perhaps because she had died during Brainiac's attack.

Up, up, and away

You can't call yourself a Superman fan if you didn't recognize Harry's instruction to Supergirl to fly the about-to-explode Overgirl "up, up, and away." That one is obvious as it has long been associated with the Man of Steel as his catchphrase to indicate when he was taking off for flight -- particularly on the radio where there weren't the visuals of comic books to help out.

It's also the name of a 2006 Superman comic book arc written by Geoff Johns and Kurt Busiek with art by Pete Woods.