Special Guest Stars Melissa Benoist as Kara Danvers / Supergirl Caity Lotz as Sara Lance / White Canary Katherine McNamara as Mia Smoak Tom Welling as Clark Kent of Earth-167 Stephen Amell as Oliver Queen / Green Arrow Jon Cryer as Lex Luthor Matt Ryan as John Constantine Elizabeth Tulloch as Lois Lane Elizabeth Tulloch as Lois Lane (Earth-75) Brandon Routh as Ray Palmer / The Atom Brandon Routh as Clark Kent / Superman of Earth-96 Tyler Hoechlin as Clark Kent / Superman Grant Gustin as Barry Allen / The Flash Dominic Purcell as Mick Rory / Heat Wave of Earth-74 Candice Patton as Iris West-Allen Guest Stars Erica Durance as Lois Lane of Earth-167 Kevin Conroy as Bruce Wayne / Batman of Earth-99 Audrey Marie Anderson as Lyla Michaels / Harbinger Wentworth Miller voices Leonard A.I. Johnathon Schaech as Jonah Hex of Earth-18 Co Starring Elias Hogewoning as Baby Jonathan Kent Benjamin Hogewoning as Baby Jonathan Kent