The official Star Wars Youtube channel posted a new Star Wars: The Clone Wars – The Lost Missions Q&A video with Dave Filoni discussing the concept of Force Ghosts…
Yoda’s story arc in The Lost Missions explores the idea of Force immortality, establishing that Qui-Gon taught Yoda how to become a Force ghost, and Yoda taught Obi-Wan. One fan asks Dave Filoni, who would have taught Darth Vader?
“That’s a big question I had for George [Lucas],” Filoni says. “And I have an answer. But I’m not going to give it to you.” Filoni points out however, that it does have to do with a change Lucas made in the Special Edition of Return of the Jedi, which sees Anakin reverting to his young self in death. “It doesn’t make sense mythologically for him to maintain the guise of the old man afterward in the Force, because he was never good…when he was that person.”
Lucasfilm’s Leland Chee points out, however, that Yoda talks to Anakin about these mysterious events — almost as if he’s planting the seed of Force immortality in his mind. “Yes, Leland,” Filoni jokes. “Darn, you’ve figured it out.”