Many spoilers ahead for all four parts of the "Crisis On Earth-X" crossover. If you haven't watched yet, you may want to check back later once you have the chance to tune in.
The long-awaited "Crisis On Earth-X" crossover event has finally aired on The CW, and we got to see just how the heroes of Arrow, The Flash, Legends of Tomorrow, and Supergirl could work together to fight Nazis. The good news is that the heroes were able to kill two of the three big bads of the crossover as well as take out the legions of Nazis who invaded from Earth-X; the bad news is that Martin Stein was killed in the process. A lot happened, and all four shows will inevitably be different in the aftermath. Read on for how each will likely change moving forward.
Oliver and Felicity tied the knot. In a surprise twist, Oliver and Felicity got married as well as Barry and Iris in "Crisis On Earth-X." Not only will Felicity presumably move in with Oliver and William, but she also can't be forced to testify against Oliver in Samanda Watson's case against him. Double win!
Earth-X Oliver is dead. Nobody on Arrow needs to worry that Oliver's evil Nazi doppelganger will be back in the future, which is a very good thing considering how often Oliver's nemeses seem to come back to haunt him.
The Green Arrow was BACK. Oliver was at his very best as a hero in "Crisis On Earth-X." He was smart, strategic, and totally badass as the leader of all the good guys. He may now be back in peak Green Arrow mode on Arrow, even if he only begrudgingly donned the hood again.
Vigilantes saved the world from Nazis. The scale of the Nazi invasion was so huge that the battle must have gained national attention. Perhaps the fact that a group of vigilantes just staved off a Nazi invasion from another world will lessen the heat on Team Arrow from the currently anti-vigilante public in Star City.
Barry and Iris got hitched. Despite their wedding getting invaded by Nazis from another Earth (and their minister being zapped to death) in the beginning of the crossover, Barry and Iris managed to get hitched at the end of the crossover anyway. Even better: it was a double wedding performed by their good friend John Diggle!
Who was that wedding caterer? A caterer at the first attempt at a wedding was behaving VERY strangely around Barry. Perhaps once the shock of the Nazi invasion wears off, Barry will start to think about who she really is.
Central City is in rough shape. Unfortunately for the folks of Central City, the Nazi invasion was all about retrieving Kara, and Kara happened to be in town for Barry and Iris' wedding. The city was damaged and a lot of people died, which means that Team Flash may have a lot on their plates in the aftermath of the crossover.
Barry let Reverse Flash go. In their latest confrontation, Barry got the better of Reverse Flash and could have struck a killing or at least crippling blow. Instead, he let Reverse Flash literally walk free, healthy and fine. This is why we don't have nice things, Barry.
Kara got some perspective. Kara had arguably the roughest ride of any hero in "Crisis On Earth-X" as she was captured, shot with kryptonite, and weakened with a red sun by Nazis who wanted to harvest her heart to put into her evil doppelganger. The upside is that it distracted her from her Mon-El relationship drama back on Earth-38, and she left Earth-1 with a fresh perspective. Yay?
Alex trusts her instincts. The terror of the Nazi invasion combined with her loneliness at attending a wedding after breaking off her engagement had Alex second-guessing her decision to end things with Maggie Sawyer. She was on the verge of deciding to go back to Maggie until Sara helped her realize that her instincts of what was right for her were right the first time around. Sanvers isn't happening again, but Alex can trust herself.
Supergirl learned some new tricks. Kara spent most of her action sequences battling her double, which means that she had to get creative to get an edge. Her sonic clap move in the first part of the crossover was pretty epic, and she may approach battles against people with similar powers -- such as Reign -- in some fresh ways.
Reverse Flash could visit Earth-38. While getting ready to harvest Kara's heart, Reverse Flash mentioned that he fought a Superman of a different Earth. Superman was fast, but Reverse Flash claimed that he was faster. Perhaps Kara's mention of her cousin will motivate Reverse Flash -- who is on the loose thanks to Barry -- to hop on over to Earth-38.
Legends Of Tomorrow
Martin Stein died. Sadly, Martin lost his life after he and a bunch of the other heroes were trapped on Earth-X. His heroics enabled everybody to escape the Nazi world and prevent Jax from dying along with him, but the Waverider is now without Martin as a scientist.
No more Firestorm. The death of Martin means that the Legends lost more than just a scientist. He was also half of Firestorm, and Firestorm was officially separated in "Crisis On Earth-X." Even if Jax returns to the team, he won't have powers for the time being.
Things just got real. The Legends are often able to avert disaster thanks to their time travel abilities and super-healing technology courtesy of Gideon. The death of Martin will probably mean a more somber and serious atmosphere on the Waverider, as everybody was deeply affected by the tragedy.
Sara is open to a relationship. Sara's hookup with Alex Danvers was played for laughs at first, but Sara went on to realize that she hasn't really opened up to anybody since she lost "her Maggie," who can only be Nyssa. Like Alex, Sara is now open to possibly falling in love again.