Lost in Space

Professor Robinson is caught in a matter transfer emission ray, and subsequently ends up in another dimension where he is confronted by a version of himself and Don. However this realm is the opposite of his own dimension, the anti-matter world, where everything in reality is twisted. The evil John returns to the family and attempts to take over the Robinsons and take over John's life. Will he get away with it, or are Will and the Robot able to defeat him, and restore the world to it's natural order.

Lost in Space's only Christmas program. Will uses an alien transporter to send himself back to earth. However, many people believe the Robinson family to be dead after hearing the ship went off course. Nobody on Earth believes him, and they lock him up with the intention of sending him to a boys' home. Will escapes the family home he's in, and wanders around these clueless bunch of townspeople, but finds carbon tetrachoride — needed for the food processors on the Jupiter. Eventually he convinces another boy, Davey, to let him out, and let him return to the planet he came from. He returns to Priplanus with this bottle. Of course no one believes his adventures until he produces the bottle, plainly labeled as coming from Earth.

John Robinson is possessed by an alien spirit. The alien forces the family to prepare to return to the spirit's home world, even if it requires he sacrifice Will to keep his secret from the rest of the family.