My son bought the Episode 4-6 DVD set, and that opened a whole new set of questions:
1. In ANH, Obi Wan tells Luke that when he first met his father he was already an accomplished pilot, which wasn't true. He was a 10-yr old slave mechanic who could drive a pod racer, not an accomplished pilot.
2. In TESB, Obi Wan tells Luke to go to "Yoda, the Jedi master who trained me." But Yoda didn't train Obi Wan, Qui Gon Jin did.
3. In TESB, when Yoda says that he can't train Luke because he's too reckless, Obi Wan says "So was I if you'll remember." When was Obi Wan ever wreckless? He's always been the poster boy for absolute obedience to the Jedi council. Qui Gon and Anakin were the wreckless ones.
4. In ROTJ, Luke asks Leia "Do you remember your mother? Your real mother?", which implies she knew she was adopted. She says "Just a little bit. She died when I was very young," which doesn't jive with the birth scene on ROTS, unless you count 15 seconds old as "very young." That also implies that Luke thought that Leia had been living with his mom while he was with his Uncle Owen.
5. A minor point, but on the director's commentary that Lucas does on the DVD of ROTJ, he says that the "ghosts" seen at the end of the movie are a result of the technique that Obi Wan and Yoda discovered, but in ROTS Yoda tells Obi Wan that he and Qui Gon discovered it.
6. For anyone who hasn't seen the DVD of ROTJ, at the end of the movie when the "ghosts" appear, the original actor who played Anakin Skywalker has been digitally replaced by Hayden Christensen. Lucas tries to justify this by saying that's what Anakin looked like when he died, but if that's the case Darth Vader should have been 100% machine.
As for Vader knowing that Luke was his son, he doesn't know that until the Emperor tells him in the beginning of TESB.