How Arrow Episode 100 Fits Inside the Supergirl Crossover

While Arrow is returning to its more grounded roots this season, the team is still making time for a superhero crossover epic with fellow CW shows Legends of Tomorrow, Supergirl, and The Flash.

The 100th episode will, in fact, be part 3 of that crossover, and executive producer Marc Guggenheim recently spoke to Collider on how Supergirl is fitting in with the Arrowverse.

“Last year, Supergirl established that The 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. Once the heroes realize that they’re up against aliens, they decide that they need an alien on their side and, fortunately, Barry knows a really nice one. I don’t think it’s a big shock that, between Barry and Cisco, and all of their experiences with Earth-2 and the multi-verse, that they can pluck her from Earth-CBS.”

While it involves all four shows, Guggenheim views it as a three part storyline, but Supergirl will heavily be involved.

There’s going to be an episode of Supergirl that ends with Supergirl going over to the cross-over. Some people call it a four-way cross-over because it involves four shows. My ulcer requires me to call it a three-part cross-over. The story that’s being told has a beginning, middle and end. It’s a beginning in The Flash, a middle in Arrow, and an end in Legends, but Supergirl is very much a part of the whole thing. So, we are crossing over four shows, but in three parts.

The three-part crossover, which will revolve around the invasion of the dominators, is still a ways off, though, so up next for the team is an encounter with Tobias Church in “Penance“. You can view the description below.

Oliver and Lyla team up on a secret mission for Diggle. Felicity finds out and disapproves of the plan and opts to stay behind. When Tobias Church launches a deadly assault against the city, Felicity must decide if she wants to send the recruits out sans the Green Arrow.

Arrow airs on The CW Wednesday’s at 8 p.m.