After who knows how many changes Lucas made to the movies, my concern comes from the, what I think is, newest dialogue between Palpatine and Vader in The Empire Strikes Back. In the original, it was not Ian McDiermid, but since the prequels have come out he has replaced the original actress who played Palpatine. I, however, am not concerned with the actor, but the dialogue that was changed. Now, the dialogue is at the link here --> Why does Palpatine refer to Luke's father as Anakin?
Now the words make it seem as though Vader doesn't know that the pilot that destroyed the Death Star is a Skywalker... The choice of the words "How is that possible" makes it seem very clear he is unaware that of the pilot's name.
This of course is all open to interpretations...perhaps he's playing dumb, or perhaps he doesn't know. But we have now canonical comics that definitively tell us Vader knows who Luke is. So why change the dialogue to the current form? These changes were made before the comics, so did the writers, who clearly know their stuff, miss this due to all the ridiculous changes made to the movies over the last 15 years?
To see the changes made to this scene, here is the youtube clip that shows the scene as well here; here