While Dr. Smith, the main antagonist portrayed by actress Parker Posey, is presumed dead after the events of the season 2 finale of Lost In Space, it is implied that she may have faked her own death in order to ensure her own survival. In one of the last scenes of the finale, a scarf and blue rubber ball that belonged to Dr. Smith are shown, insinuating that Dr. Smith snuck onto the Jupiter and stowed away in a storage compartment.
Dr. Smith, the devious con-artist whose real name is June Harris, has been the main antagonist since season 1 of Lost In Space. A manipulative criminal posing as a therapist, Dr. Smith consistently puts the lives of others at risk, especially when her own safety or the secret of her true identity is threatened. In the second season of Lost In Space, however, it seemed Dr. Smith was beginning to change into a more selfless person thanks to the positive influence of Penny Robinson (Mina Sundwall). Through Penny’s coaching, not only did Dr. Smith save the life of Professor Jackson (Rob LaBelle), convincing the claustrophobic teacher to take shelter inside of a storage unit before their section of the ship got severed from the Resolute, but she also teamed up with John Robinson (Toby Stephens) to help infiltrate the Resolute’s chain of command.
Despite growing as a character throughout Lost In Space season 2, Dr. Smith reverts to her usual cowardly demeanor after she learns a horde of alien robot ships are headed for the Resolute. After Judy (Taylor Russell) proposes a last resort plan that will allow the 97 children aboard the Resolute to escape, Dr. Smith tries to steal the Jupiter transport intended to take them to the colony on Alpha Centauri until Will’s (Maxwell Jenkins) robot stops her. When Dr. Smith asks the robot to give her one good reason why she shouldn’t launch the ship, the robot instead gives her five as he rearranges the lights on his face to form five individual dots representing the Robinsons.
After communicating with the robot, Smith appears to have an epiphany that the Robinsons are the closest thing she has to family and seems to desert her plans to escape. When the hostile robots attempt to break out of the magnetic field containing them, Dr. Smith, in a rare act of heroism, volunteers to enter the magnetic field and stop the robots from cutting the power. As Dr. Smith’s broken helmet and empty suit drift outside of the airlock, the viewer is led to believe that the magnetic field crushed her metal suit and she died trying to buy the Robinson children time to escape. However, in the final scene of the finale, the robot discovers a rubber ball and scarf in a storage compartment onboard the Jupiter that not only belonged to Dr. Smith, but were items she had on her person when she died.
While it's pretty clear Dr. Smith staged her death, she would've had a short window of time to return to the Jupiter before the ship evacuated. With the additional distraction of the oncoming horde of alien robots, Dr. Smith might have had the opportunity to sneak onto the Jupiter transport and stow away inside the storage unit, repeating a similar plan that occurred in episode 6, “Severed.” When Dr. Smith, Penny, Vijay (Ajay Friese), and Professor Jackson got trapped in a section of the Resolute where the rust infestation was beginning to spread, Don (Ignacio Serricchio) suggested they take shelter in a storage unit, which are temperature controlled and have a heater built into the base. If Dr. Smith removed the heater, as Vijay did in episode 6, she could have stowed within the base of the storage unit, remaining undetected as the Jupiter evacuated the Resolute.
While fans will have to wait until season 3 of Lost In Space to find out officially if Dr. Smith survived, the cliffhanger makes you wonder at the character’s growth going forward in the series since Dr. Smith doesn't appear to have changed beyond her selfish survivalist instincts.