Special Guest Stars Victor Garber as Dr. Martin Stein / Firestorm Guest Stars John Wesley Shipp as Dr. Henry Allen Robbie Amell as Ronald "Ronnie" Raymond / Firestorm Andy Mientus as Hartley Rathaway Melise as Linda Park Britne Oldford as Shawna Baez Micah Joe Parker as Clay Co Starring Matt Yanagiya as Man Scott McNeil as Julius Doug Chapman as City Worker #1 Crystal Mudry as Woman Tristan Shire as Bartender J. Douglas Stewart as Fire Chief Will E. McDonald as Truck Guard #1 Theo Wiersma as Karaoke Bar Patron Fraser Aitcheson as City Worker #2 Jerry Trimble as Marcus Stockheimer