They need to fix the blue screen stars being in focus when the background of the throne room is out of focus. Always bugs me. They could have tied in Han's rescue to the rest of the film more. Maybe while undercover, Lando finds out about the Empire secretly moving lots of construction material, and a darker, less idealistic Luke wants to pursue that information instead of rescuing Han. Leia would want to risk doing both. It would give Lando more to do and provide some character conflict/insight with Luke and Leia.