Leonard Maltin Interviews George Lucas, Part 2: The Empire Strikes Back

In the second installment of Leonard Maltin's interview with Star Wars creator George Lucas, the two discuss the critically acclaimed Star Wars sequel, The Empire Strikes Back.
Maltin calls The Empire Strikes Back "a totally successful film in its own right, as well as one of the most popular sequels ever made." After the release of Star Wars, a success beyond Lucas' expectations, Lucas was ready to continue his story. Originally, his script for Star Wars was massive, and he cut it into segments; The Empire Strikes Back was just the next phase of a story he'd already plotted.
Maltin asks about the biggest overall difference between Episode IV and Episode V, noting that the latter is considered a darker picture. "It is a darker film," Lucas says, "because in the first act you introduce everybody, the second act you put them in the worst possible position they could ever get into in their lives...and then the third act, they get out." There was no major technological advance, the filmmaker says, just refinement. But The Empire Strikes Back gave him an opportunity to do more stop-motion effects and expand the scale of the Star Wars universe.
When Lucas created Yoda, he wanted him to be very small, but then had to figure out how to translate that to film. The idea was to bring him to life as a puppet, and he asked his friend Jim Henson to play the role. Henson was busy at the time, and suggested his longtime collaborator Frank Oz. Lucas loved that idea, and notes that everyone involved was excited about Yoda.
Maltin and Lucas also talk about the saga's music, with Lucas revealing that Steven Spielberg suggested John Williams as composer, and dispelling the rumor that he originally wanted to use existing classical music.
And as for the classic cliffhanger involving who Darth Vader really is? Lucas intentionally left it ambiguous, wanting people to debate whether or not it was true.