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 Lauren Ambrose as Agent Einstein Barbara Hershey as Erika Price Alan C. Peterson as Mr. Y Anjali Jay as Dr. Joyet Co Starring Sandy Da Costa as Alien Fiona Vroom as Young Cassandra Naiah Cummins as Nurse Erica Govier as Young Erica Jeremy Schuetze as Young CSM Harry Han as Male Paramedic Jett Klyne as Young Spender Arggy Jenati as Female Paramedic Alexandre Campion as Young Mr. Y Uncredited Mike Dopud as Mr. Y's Henchman
