Guest Stars William B. Davis as Cigarette-Smoking Man Annabeth Gish as Special Agent Monica Reyes Chris Owens as Special Agent Jeffrey Spender Robbie Amell as Agent Miller Barbara Hershey as Erika Price Lauren Ambrose as Agent Einstein Alan C. Peterson as Mr. Y Anjali Jay as Dr. Joyet Co Starring Sandy Da Costa as Alien Fiona Vroom as Young Cassandra Harry Han as Male Paramedic Jett Klyne as Young Spender Naiah Cummins as Nurse Arggy Jenati as Female Paramedic Erica Govier as Young Erica Jeremy Schuetze as Young CSM Alexandre Campion as Young Mr. Y Uncredited Mike Dopud as Mr. Y's Henchman
