To tell the truth, I never liked the look of "the cave" in ESB. I didn't like that it looked like some sort of hidden or long buried structure. It should have just been a cave, nothing more.

I see Luke coming into the cave and then being met by fog. After a few moments, Vader appears out of the fog.

That's how I would've done it if I was the director. Vader is merely a manifestation of Luke's mind since obviously he is not there. Luke is surprised/shocked to see Vader, but we all know he shouldn' be since he saw exactly what he wanted to see. Making it look more in line with what I would would call a "dream-like" sequence would have been a better choice for Lucas/Kersh in my opinion.

Also, I find it strange that people who don’t like the midi-chlorian thing always seem to want an explanation as to why “that place is strong with the dark side of the Force." Who cares? I know that in my life I’ve been in places and even whole cities that have given me a weird, even downright cold vibe. I don’t find myself asking for an explanation.