I think it all came down to an oversight . Films are often shot out of sequence , and in the documentary From Star Wars To Jedi The Making Of A Saga , George Lucas states that when it came down to the battle between Vader and Luke in the Emperor’s throne room , he needed a reason to make Luke turn on Vader and get angry and use the darkside for a moment . That is when he decided to make Leia his sister . So, I am guessing the previous scene during the Ewok village at night played into this . The scene with Han and Leia after the Death Star explosion is the one that seems to me to have been played for laughs .