I actually really enjoyed this, I haven't seen the movie for years and I thought the 3D conversion was pretty decent compared to some modern movies where they slopped through it.
Also, on the big screen, it becomes easier to notice unexpected things.
1. When the group goes into the haunted woods to find the Wicked Witch (after getting the quest from the Wizard), The Scarecrow is actually packing iron. Yes, he is holding a gun for about 30-60 seconds in there. wtf? It's a fantasy world! Hilarious.
2. I could have sworn I saw some shape moving for a second in front of the cabin, and then later one waaaay in the distance in the center around one of the trees, when the Woodsman, Scarecrow, and Dorothy hit the road after the Witch firebombs Scarecrow and leaves. I have no idea what this was supposed to be or what purpose it served.
3. The makeup on Scarecrow (face) was pretty exquisite. Actually, it was on all of them, but the scarecrow it was hard to tell where the burlap texture began and ended on the contours of his face.
4. Um.... tin does not rust. Rust is the oxidation of iron. The Tin Man's outfit DID actually have a lot of rust on it until he's cleaned off in Emerald City, and it was very detailed. Also, his butt was made of some soft plasticky material (like a garbage bag), while other parts of his costume seemed to be stiff metal or plastic.
5. On the big screen, it was obvious that the Tin Man's right eye (on your left) in one scene is yellow compared to the whiteness of the other one. If you know anything about the makeup used, well, it's known they stopped shooting for a few days because he got an eye infection from the makeup. (He fared far better than Buddy Ebsen, though!)
6. You can see the outline of the trap door in Munchkinland where the witch came out of the floor. I wasn't aware they actually had a stand-in for some of the witchery. (Apparently Hamilton got burned at one point and knew she'd never work again if she sued, so she came back but under condition of "no more fire.") Sadly, the stand-in during the skywriting shots was burned by an explosion of the pipe she had been forced to sit on to film those bits; she had permanent scars on her legs, and yet another stand-in took the stand-in's place,.
7. There's a lot more interplay than I had even remembered between the Oz scenes and Kanasa scenes, in terms of tongue-in-cheek dialogue.
8. Henry and Em are the only two main characters I think who are not represented in Oz. Pretty much they represent Home to Dorothy -- she wasn't able to "take them with her" into Oz. Also, kind of amusing that Ben in "Lost"
9. The WWW's colors are red and green -- she is green, and a few instances of her magic is green, but she also uses a bright crimson red distinctively as part of her magic. Even in her crystal ball, it goes from green to red back to green, I believe, and all of her smoke clouds are this distinct color of red, and of course there is her obsession with fire. In Raimi's "Oz the Great and Powerful," the same hue of red shows up with the WWE is mixing things and a small cloud of smoke arises.
10. Toto gets away twice -- once from Almira Gulch, once from the WWW.
11. The place where the backdrops were is even more distinctive (essentially when Dorothy is going down the Yellow Brick Road). They seem to be fairly obvious, and then of course there is always a cut-scene right when Dororthy reaches what is actually a backdrop.
12. So is Frank Morgan really playing five different characters, or are some of the character SUPPOSED to be the Wizard himself in diguise? I suspect at least the final doorman (if not more) is actually the Wizard pretending to be another character to screen his own visitors; the first doorman also seems to be that way.
13. They didn't include the "horse of a different color" song, although the horse makes an appearance. I also swear that there are horses in the background countryside in "Oz the Great and Powerful," that are changing color.
14. For being 30's tech / special effects, the tornado from a distance actually looked really cool on the big screen. Aside from one perspective shot where its size was a little off, I was impressed with what they accomplished.
If I think of more, I'll post it. But there's a huge difference in just detail that you get from a large screen that you don't pick up on a small home screen.