Special Guest Stars Grant Gustin as Barry Allen / The Flash Stephen Amell as Oliver Queen / Green Arrow Carlos Valdés as Cisco Ramon / Vibe Danielle Panabaker as Caitlin Snow / Killer Frost Caity Lotz as Sara Lance / White Canary Tom Cavanagh as Eobard Thawne / Reverse-Flash Tom Cavanagh as Harrison Wells Emily Bett Rickards as Felicity Smoak Jessica Parker Kennedy as Wedding Caterer Jesse L. Martin as Joe West Stephen Amell as Oliver Queen (Earth-X) / Dark Arrow Keiynan Lonsdale as Wally West / Kid Flash Dominic Purcell as Mick Rory / Heat Wave Candice Patton as Iris West Victor Garber as Dr. Martin Stein / Firestorm Franz Drameh as Jefferson "Jax" Jackson / Firestorm Guest Stars Danielle Nicolet as DA Cecile Horton Patrick Sabongui as Captain David Singh William Katt as Minister Isabella Hofmann as Clarissa Stein Christina Brucato as Lily Stein Co Starring Mackenzie Gray as Greggor Paul Herbert as Scientist Jeremy Schuetze as Rob Chris Walters as Norman Guard Robyn Bradley as Wedding Planner Anthony Ames as Angry Boss Jay MacDougald as Guard Andrea Pizarro as Manicurist Uncredited Melissa Benoist as Kara Zor-El (Earth-X) / Overgirl Mehcad Brooks as Guardian (Earth-X)