While last year's crossover was treated like two separate episodes with a common thread, Kreisberg explained they took a different approach this time around: "Given the success that we’ve had previously and how people are viewing this as much more of a collective, shared universe, we felt emboldened. And our partners at CW and Warner Bros. were more supportive so we were able to really have a two-hour true event with one story and one villain and one storyline and not having to worry so much about the mechanics of how it would air."

We know that Kendra (Ciara Renee) is Hawkgirl (due to Cisco's visions), but it's not long into the crossover that we meet Hawkman, aka Carter Hall, played by Falk Hentschel. The actor brings an impressive ownership to the character from his first appearance – but when asked about how it felt to wear the Hawkman outfit for the first time, he smiled and said: "It's a very simple answer. It was awesome!"

While you'll have to wait to see how Kendra truly comes to know (and believe) who she really is, the relationship between her character and Carter is a fun one. "In my mind they're like a bickering old couple," Hentschel shared, having already shot episodes of Legends before filming The Flash/Arrow crossover. "He's gone through 4,000 years of loving her and having her love him back…she doesn't know about it yet, though, so there's always this fun dynamic."

You can't have good heroes without a good villain, right? Savage (Casper Crump) proves to be one of the more formidable we've ever seen on either Flash or Arrow. While the villain does have a plan we see play out in the crossover episode, the producers said he also has a bigger desire, but we’ll have to wait a bit to find out what that is. "He has a very clear plan and trajectory," Guggenheim explained. "The thing about Vandal is that for him, a lifetime is an eye blink. He thinks in thousand-year-old terms. He's very much a master of the long con. Yes, he does have his own personal agenda vis-a-vis the Hawks, but he's got much bigger plans for the world." But trust you’ll get a sense for just how determined and evil Savage is.

Doing two shows was one thing ... but adding Legends to the mix added much more to crafting the narrative that serviced everyone' it was also a physical challenge for everyone involved. "Certainly for the actors," Guggenheim said. "Just being asked to shuttle from literally one set to two other sets, oftentimes in the course of a single day to the crews of the three different shows to the ADs, I really do have to give credit where credit is due to the ADs of Legends, Flash and Arrow.”

Much like Hentschel enters into the show as a fully formed character (as opposed to a new character whose journey is becoming a hero), Sears expressed he’s also enjoyed that element about Jay Garrick: "It’s wonderful just to drop in, in a universe that already exists and to slowly have these things be revealed over time. It's really exciting and especially to come into a world where already so much has happened and there’s a voracious appetite by the fans to peek in on the guys and gals around STAR Labs. For me, the most ideal way to join a show."

With all the talk about Vandal Savage and the Hawks, don't you worry that we’re not going to see much in terms of the budding relationship between Barry and Patty (we do) and Oliver and Felicity (we do…big time), as well as more with Harrison Wells' presence, Malcolm Merlyn and you’ll also see just how awesome the groups of Flash and Arrow work like a well-oiled machine. Bonus: Can you guess who from the Arrow team has yet to meet the Flash? You'll find out.