"Cyd and Shelby Strike Back" is the eleventh and twelfth episode of Best Friends Whenever. It aired on November 27, 2015.


When Shelby and Cyd discover inventor and GDD CEO Janet Smythe is behind the future lab, they decide to fight back and travel to the past to stop Janet from starting the corporation. Their plan seems to work until they realize they also stopped other major events and causing their future even worst from happening in their lives, including them living separate from each other and Barry and Marci falling for each other.