Special Guest Stars Stephen Amell as Oliver Queen / Green Arrow Grant Gustin as Barry Allen / The Flash Emily Bett Rickards as Felicity Smoak Melissa Benoist as Supergirl / Kara Zor-El / Kara Danvers David Ramsey as John Diggle Danielle Panabaker as Caitlin Snow Carlos Valdés as Cisco Ramon Guest Stars Christina Brucato as Lily Stein Donnelly Rhodes as Glasses Lucia Walters as The President Co Starring Jacob Richter as Younger Glasses