yep, it was the same planet set for both pilots. Kirk fights Mitchell pretty much where Pike was kidnapped on Talos IV. It's an amazing set, very gloomy and realistic.
The episode itself is outstanding, both versions of the episode are equally great (the differences are merely cosmetic anyway). I'm convinced Shatner's performance really put this episode over the top and sold the series. He's amazing from start to finish. He's the star here and he inhabits Kirk from moment one.
I actually always liked Spock's makeup here. Very severe and extremely satanic (yes, I know that was a major issue).
A great pilot and a home run episode, to this day I feel this should have been the first episode aired. I feel the changes would have been less jarring if they didn't already air two episodes in the finished format. Plus, killing off Kirk's best friend makes more sense in episode 1 than in episode 3, where people could have wondered where this guy was for two episodes.
Interesting tidbit: Spock and Mitchell have worked together for years at this point. Since Spock was already on board when Kirk took over, that either means Mitchell was there too, or this episode isn't THAT early into the 5 year mission.
Or it just means nobody figured anyone would be talking about it 46 years later...