In the Emerald City, the city's doorman, the guard to the Wizard's sanctum, and the cab driver with the "horse of a different color" are all played by the same actor: Frank Morgan, the guy who played the Wizard himself. This seems like just getting extra-mileage out of an actor, until you realize that it's all probably part of the Wizard's con. Since no one can be allowed to see how ordinary the Great Oz really is, in order to govern the Emerald City he puts on a disguise, pretends to be one of his own subordinates, and "relays" orders from the Wizard to the rest of Oz.
This also lets him see and hear what's going on for himself instead of relying on messengers and such. This way, people will be amazed at the Wizard's omniscience.
This didn't hit me until later. In the books, they can see the green glow of the city a mile away and it's easy to assume the entire city is made of emerald. You might wonder where they got all that rock. Then you realize that when they actually get to the city, they have green-tinted spectacles locked to their eyes that aren't taken off until they leave. In fact, *everyone* in the city wears those same specs.
When I was a kid, I always wondered why the Witch expected Dorothy to surrender just because she demanded it via skywriting. As an adult, I realized that the message wasn't "Surrender, Dorothy" but "Surrender Dorothy"—she was demanding that the residents of Emerald City hand over the girl, with an implied threat should they not deliver. Dorothy was a stranger to the city, but they all knew how powerful and dangerous the Witch was.
Scarecrow's "brainy" statement when he gets his diploma: "the sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side." This is incorrect mathematically (should say a right triangle) and I always assumed it was writer error. However, it is made clear that the Scarecrow was already intelligent and the diploma did not change anything other than his confidence. And his intelligence does not come from book-learning or schooling of any kind, so of course he wouldn't know the correct formula. He just said it to FEEL smart. Of course the other explanation is that the whole story is Dorothy's dream, and she's the one who got the math wrong, being a kid and all.
Even if the WMG is wrong and Glinda isn't a Villain with Good Publicity, she's certainly no angel. First, she swipes the Wicked Witch of the East's shoes and pawns them off on Dorothy - thus depriving the WWotE's only remaining relative (the Wicked Witch of the West) of her sister's last remaining possession, which is pretty repugnant. And Glinda's just warming up, too. She then taunts the Witch of the West and makes sure her rage is focused on Dorothy - who, let's remember, might've committed manslaughter but certainly didn't ask to be brought to Oz via tornado and didn't exactly aim for anything when her house landed. She then sends Dorothy on a fairly pointless quest to the Wizard of Oz; yes, it's important to the story and yes, Dorothy learns a lot about herself and gains several new friends. But Glinda's excuse for not telling Dorothy, right off the bat, that she was now the owner of a pair of slippers that could teleport their wearer? "You wouldn't have believed me." As if that excuses not mentioning it anyways. Yep, you wouldn't have believed her, Dorothy - never mind that you just splatted one Witch with your house, witnessed a pair of spectacular entrances by both the Witch of the West and Glinda, got threatened by the WWotW, and were lauded for your house-fu skills by Munchkins. Nope, no reason to believe that your ruby slippers might teleport you anywhere. It's due to Glinda, in fact, that Dorothy is placed in life-threatening danger several times throughout the movie - the Witch of the West would have gone away quietly if she'd been given her sister's slippers, after all, and it's Glinda who sends Dorothy on a quest outside of Munchkinland...which is also a zone of protection that the Witch of the West can't harm Dorothy within. This also combines with Adult Fear when you consider the fact that most parents probably worry about their kids falling into the hands of some pleasant-faced stranger who'll happily sell them down the river.
For heavens sake! Glinda isn't a Villain with Good Publicity! She should be in the Fridge Brilliance section because she is the Obi-Wan Kenobi/Master Yoda of the Land Of Oz! She never did anything malicious or sinister! Also, the quest she sent Dorothy and her friends was not pointless. Dorothy needed to undertake it in order to unlock the power of the Ruby Slippers. Glinda was just Dorothy's teacher. She's just very very subtle about it, that's all.
Also, if you've read the book (like this troper has) you'll realize that possibly in the movie, Dorothy wasn't in any real danger as well. In the book, The Good Witch of the South in Munchkinland kisses Dorothy on the forehead, thus casting a charm spell of protection on Dorothy. If you watch the movie & watch carefully, Glinda The Good Witch On The North (standing in for the Witch Of The South), after she says, "....the sooner you get out of Oz, the safer you'll sleep, my dear..." she kisses Dorothy's forehead. This may be a Call Back to the book, which folks in 1939 may have been more familiar with. Thus the whole cynical, postmodern "Glinda was the real villain/Why would Glinda put Dorothy through all this crap to begin with?" is really silly. Glinda was like a Zen Master, Guru or The Obi-Wan, she wanted Dorothy to figure out the lesson by herself & save the Land Of Oz in the process. Real character-building!
It's unlikely that the Witch would have "gone away quietly" with the Ruby Slippers. After all, her sister had just been killed by Dorothy's house; in fact, her first words to the girl are a threat of violence: "I can cause accidents too!" And this is before she tried to reclaim the Slippers. The witch had it in for Dorothy from the moment they met.