Father's lightsaber

Why: Obi-Wan mentions to Luke that his father wanted him to have his lightsaber when he was old enough, but there is nothing in ROTS to suggest that. Heck, Anakin thought Luke had died along with his mother. The dialogue could be fixed slightly to accommodate this so that Obi-Wan doesn't look like a complete liar in the OT.

How: Make Obi-Wan say, “I wanted you to have this…” by just cut and pasting him saying, “I,” from somewhere else. This has already been done by fans, and quite professionally I might add.