Melissa Benoist, Grant Gustin and Stephen Amell talked about what it was like to shoot the highly anticipated crossover event between “Arrow,” “The Flash,” “Supergirl” and “Legends Of Tomorrow” during The CW superheroes panel at EW PopFest on Saturday, Oct. 29.

“It was really cool.” Amell said of his experience doing the crossover. “We had our individual scenes but then we had scenes where there were like 20 superheroes there … in this big airplane hanger. I think the fans will feel like this is a big three hour-like movie we’re putting on.”

When asked how it was different from other crossovers that they had done before, Gustin said: “It was just a lot bigger. We have like 17 characters in multiple scenes then almost everyone interacts with every other character in a certain point. It’s huge.”

Benoist said that her character, Kara, “had good interactions with almost everyone” in the crossover. “I think Kara just wants to be accepted … like a part of the cool kids,” the actress said.

As for how she felt about temporarily joining the Arrowverse for the crossover, the “Glee” alum said: “It was so fun to just be in this big group setting. It was like this infectious environment. It felt really cool.”

Earlier this month, “Arrow” and “Legends of Tomorrow,” executive producer Marc Guggenheim teased how Kara will end up in the Arrowverse for the crossover.

“Last year, ‘Supergirl’ established that Flash was able to make his way to what I call Earth-CBS, and it stands to reason that, with the proper breach technology, the reverse can happen,” Guggenheim said (via Entertainment Weekly). “[So] once the heroes [in the Arrowverse] realize that they’re up against aliens, they decide that they need an alien on their side. Fortunately, Barry knows a really nice one.”

Given Barry and Cisco’s (Carlos Valdes) experiences in traveling to and from Earth-1 and Earth-2 last season, the exec producer said it won’t be long before the two realize that they can take Kara from her Earth to their Earth.

The heroes of all four series will team up to defeat the alien race Dominators in the crossover. In the comics, the Dominators see the unpredictable evolutionary tendencies of Earth’s metahumans as a threat to the state of the universe, so their ultimate goal is to get rid of all the metahumans living on Earth.

Guggenheim told Superhero Insider that the Dominators’ agenda in the crossover is quite similar with their objective in the comics. “I will say that their goal is very closely related to what was established in the comics, and it does have to do with metahumans,” the exec producer said.  “It’s very, very faithful to the comics.”

The crossover event is expected to air sometime in November.

Melissa Benoist, Stephen Amell and Grant Gustin Melissa Benoist, Grant Gustin and Stephen Amell teased the highly anticipated crossover event between “Arrow,” “The Flash,” “Supergirl” and “Legends Of Tomorrow” at EW PopFest this weekend. Photo: Getty Images/Alberto E. Rodriguez