This week's episode of "The Flash" was full of cameos and other surprises as Barry (Grant Gustin), Cisco (Carlos Valdes) and Dr. Wells (Tom Cavanagh) traveled to Earth-2 in the first of a two-part story arc.

Viewers got to see a glimpse of other characters such as Jonah Hex, Gorilla Grodd,1990s Flash—played by John Wesley Shipp, who also plays Barry's father on the CW show—and Supergirl (Melissa Benoist) as the trio hurtled toward Earth-2.

Upon arriving, Barry, Cisco, and Wells found out that on Earth-2, Barry and Iris are married, while Caitlyn and Ronnie are the evil metahumans Killer Frost and Deathstorm. They are led by Reverb, Cisco's evil counterpart, who reports to Zoom. Barry ends up being captured by Zoom, who wants to keep his powers for himself.

Speaking with The Hollywood Reporter, executive producers Todd Helbing and Aaron Helbing previewed the second part of the story arc titled "Escape from Earth-2," which will air next week on The CW.

Todd said that the central story is Barry trapped by Zoom, while back on Earth-1, the rest of the S.T.A.R. Labs team deal with the Geomancer.

"The Flash is locked up in a cell, so they really don't have a way to deal with him now that they're Flash-less," the producer explained. "They have to come up with a new plan and we get to see somebody step up to the plate."

Meanwhile, Caitlyn is working on the Velocity drug and Jay is still refusing to take it since he revealed that he got addicted to it before, but Earth-2 Jay will find himself being the hero that he always was meant to be. Todd also revealed that Cisco and Wells will be plotting to free Barry, and they seek help from an unlikely source as they do their best to set up the rescue mission.

"The Flash" airs Tuesdays at 8 p.m. on The CW.