the magic goes away
It took me two watchings to process this ending, and the second time--seeing just that section, without any of the build-up to convince me of its rightness--I started to feel really uncomfortable about it. Then it hit me how subversive an ending it was for someone who grew up with traditional children's fantasy.
In the books I grew up with, you always had to go back to reality in the end. (The only exception I can think of is the "Oz" books, and the rules of that world were so wacky and inconsistent, it hardly counts.) Sometimes it's dramatic: you give up your magic for true love. Sometimes you get too old for magic kingdoms. Or the magic just runs out or gets used up. Maybe if you're really lucky you'll get a second adventure--but that one will end, too. The ending is often seen as not only inevitable, but in some ways desirable.
Here's a fairly typical ending, from Magic in the Alley by Mary Calhoun. This I think could count as a "give it up for love" story: Cleery has used up the very last of her found magic to make her friend Crow able to fly again:
As they stood in the alley, the wind passed away through the lane of trees, into the sky beyond. The leaves stilled on the trees. The window of sky belonged to Crow. They turned and walked back the way they came.
Knobs said, "Cleery, there are still good alleys to explore. Even though summer is done, there are still Saturdays and alleys."
She smiled at him. "I know." There were still alleys, still Knobs, she still liked being Cleery.
Cleery then discovers a note that her box of magic should be delivered to a shop in the "next town west." Like the amulet in Half-Magic, it will somehow regenerate its magic for a new person to find. The magic always--make that almost always--gets to go on, it's just the people who don't get to keep it.
It pisses some readers off. I wonder if one of the reasons the "Harry Potter" books took off so successfully was that they turned this idea around? The world of magic becomes the place where our hero is the most himself, the most happy, the most alive. YA paranormal stories often involves a normal person becoming part of a supernatural world--very rarely does the opposite happen.
I was never one of the pissed-off people. I tended to accept what I read. But thinking of the show ending as subverting the pro-reality message somehow made me like it a lot more.