ray_afraid said:

Another change I'd like to see (and much more do-able than my last suggestion) is to remove the shot of Vader stepping on Obi-Wans robe after he disappears. It makes it seem that Vader has no idea what just happened. If he really did "help the Empire hunt down and destroy the Jedi Knights" then not only would he know what happened, he probably expected it. Right?

It was obviously new to Vader. The whole disappearing act was a neat story device in the OT and clearly no thought was given to its role in an imaginary history. Then again, even in the PT, Lucas didn't have disappearing Jedi (it would have been an interesting scene if Anakin's saber had dispatched the younglings like popping bubbles).

Both Yoda and Obi Wan had made peace with death. It's plausible that Vader never encountered a Jedi who died in such a way - particularly the ones he pursued. Its easy to overthink all this, but I like that it confounded Vader. His knowledge of the Force probably gave him insight into what happened but still a plausible surprise.