Perhaps the most exciting thing in the half-season of The CW’s two DC superhero juggernauts, Arrow, and The Flash, is happening tonight, when members of Team Arrow make their way to Central City, and tomorrow night, when members of Team Flash to head to Starling City. Even though those sets are literally only a few hundred feet away from each other, the tones of the two shows set them miles apart. So, how will it be with the first big and true crossover in DC TV history since the Green Lantern and Kato made their way to campy Gotham City, and what can fans of both expect to see? We spoke to the heroes themselves, Stephen Amell and Grant Gustin, to get the inside scoop.

Amell has long been a fantastic ambassador for his show for its first two seasons, but now he’s a champion of his own show and The Flash, knowing exact episodes where things occur, which is amazingly impressive. He told us that an idea he had for Oliver actually would fit best in the Flash portion of the crossover, “I can’t tell you anything about it other than it relates to Central City and when I saw it in the Flash script, it ended up being really actually quite gratifying,” Amell said, “It ended up being a cool idea that we were able to utilize me for because we were doing a crossover with the Flash.”

He’s also very aware of the shows being in the same universe, but separate, and he treated his visit to the TV Central City with the utmost respect. Amell shared, “We are very much guests in Central City and very much the road team in Central City, just as Grant and the whole Flash team are our guests [in Starling City]. And we talk and we delve into the differences between Central City and Starling City.” He also shared that because the shows are so different, the crossover allows for some revelations to take place. “Starling City and Central City are very different places. So when I go to Central City, it’s very much, ‘Alright, I’ll tag along. We’ll do things your way.’ And then the very next night, in our episode, it’s ‘I’m sorry, we’re not in Central City anymore. We’re doing things my way. Things are different here.’ So it’s a really interesting check point for both shows, because we’re able to teach these big lessons to the characters. So hopefully Oliver comes out of his trip to Central City having learned something and Grant comes out of his trip to Starling City having learned something as well.”

Grant Gustin has picked up his newfound mantle as DC superhero and, if you’ll pardon the phrase, ran with it. In only seven episodes, he’s established who his version of the classic Silver Age Flash, and it’s very different from Amell’s Oliver Queen, of which the two actors are fully aware. Gustin said, “Oliver and Barry are so different and me and Stephen are just really different and we really get along outside of work. And it’s been fun. Barry and Oliver are kind of butting heads but we’re seeing them learn how to work together. It’s really funny because they’re so different so the conversations they have are hilarious.”

Gustin was also in awe of the way action is done on Arrow versus how it’s done on The Flash. “We do a lot of plate shots that are empty shots over the area that we’re going to be in and they’re putting us in later in post. I do a lot of the fighting that…I don’t have to do it full speed and they’ll ramp it up. Then a lot of people have to freeze and I keep moving and I have to clear frames, step back into frames. It’s really tedious stuff that we have to do.” He also added that he’s in awe of the physicality of Arrow‘s fight scenes. “They’re doing everything! They learn the fight choreography and they shoot it from the perfect angles and what you see is what you get.”

The amount of effects done for The Flash was a wholly new experience for Amell, who is certainly not used to the slower pace of CG-involved action, specifically in the episode “Flash vs Arrow” which will air Tuesday night. “You can extrapolate and bet based on the title that we fight,” Amell said, “And that whole dynamic, which took place over three nights of shooting, was a very new and different experience for me just from a technical standpoint because The Flash has so many effects.” He also said that he had to learn to slow his movements down…way, way down. “I actually had to do a move where I’m going to punch and I had to punch in slow motion and literally do slow motion faces and all that stuff.”

One thing that both Amell and Gustin agree on 100% is that their favorite aspect of the crossover is a particular actor and character. “David Ramsay is, like, the funniest person in the world,” Gustin says through a grin. “Think about Diggle seeing the Flash and who Diggle is and having to accept that this is reality. And he just plays that so well and so funny. It’s great.” Amell seconded that: “The unequivocal highlight of the entire crossover for me is David Ramsey. I could not keep a straight face during any of David Ramsey’s lines during the crossover to The Flash. It destroyed me.”

And, just for you people out there who like to pay very close attention, Amell says there is a very particular thing fans should look for: “I think that one of the most interesting parts about the whole episode [“Flash vs. Arrow”] is an observation that Oliver makes about Harrison Wells.”

We’ll have to watch to find out what he means. The Flash episode 108, “Flash vs. Arrow” airs Tuesday night at 8/7c, and Arrow episode 308, “The Brave and the Bold,” airs Wednesday night at 8/7c, both on The CW.