There were parts of the OT, and even some opened in the PT, that never really got clarified, explained, or fully utilized. Without spoiling scenes or details from The Force Awakens, what could be addressed or mentioned in those future films? (I don't think this thread is best put in those threads' sections) If things could be spoilers, maybe they would best be added to a current thread there (or moving this thread).
For example, the rock entryway on Dagobah really was a subtle detail that never seemed to be explained (it couldn't really be part of Yoda's pod that landed on the planet). The whole Sifo Dyas thing is still confusing to me.