Special Guest Stars Willa Holland as Thea Queen Paul Blackthorne as Detective Quentin Lance Caity Lotz as Sara Lance Grant Gustin as Barry Allen Guest Stars Katherine McNamara as Mia Smoak Venus Terzo as Dr. Elisa Schwartz Joe Dinicol as Rory Regan Joseph David-Jones as Connor Hawke Bex Taylor-Klaus as Cindy "Sin" Simone Laara Sadiq as Emily Pollard Co Starring Jack Moore as William Clayton Eliza Faria as Zoe Ramirez Evan Roderick Anderson as Officer Nick Anastas Jessica Heafey as Documentarian / Marcia Pedowitz Uncredited Kelsey Grammer voices Narrator