Quick note: Danielle Panabaker and Carlos Valdes will appear as Caitlin Snow and Cisco Ramon on tonight’s episode of Arrow. The characters, based on Killer Frost and Vibe, are members of the Flash supporting cast and will appear as regulars on that show if the CW picks it up as a series. See also the latest DC All-Access episode:
The CW originally planned to make Arrow episode 2.20 into a back-door pilot for The Flash, bringing back Barry Allen from his two-episode guest spot and showing him after he gains super-speed. The network liked the character so much that they ordered the stand-alone pilot that’s currently in production.
But they’re still establishing background for the Flash spin-off, as two members of the supporting cast are confirmed for Arrow episode 2.19: Danielle Panabaker and Carlos Valdes will appear as Caitlin Snow and Cisco Ramon, scientists based on Killer Frost and Vibe from the comic books. (via FlashFans.org)
Update: THR has more information. Guggenheim explains that bringing in the S.T.A.R. Labs scientists keeps the Flash elements present in Arrow in a much more interesting way than showing Grant Gustin lying in a hospital bed with his eyes closed.
— Arrow – GreenArrowTV (@GreenArrowTV) March 17, 2014