A lot of people expressed confusion at the scene where Artax drowns in the Swamp of Sadness. However, horses are very good at sensing human emotions, which is one reason why they're used as therapy animals. That's probably why Artax couldn't stop the sadness from getting to him.
That, and as the book clearly states, the Swamp amplifies a person's sorrow just by being in it, followed by drowning. Atreyu only didn't sink because he had the AURYN.
The movie breaks the fourth wall near the end, when the Princess is explaining to Atreyu that she is aware of Bastian and knows what he must do. "He doesn't realize he's already a part of The NeverEnding Story. Just as he is sharing all of your adventures, others were sharing his. They were with him when he hid from the boys in the bookstore. They were with him when he took the book with the Auryn symbol on the cover, in which he's reading his own story, right now." She's referring to the film's audience. The implication is that there is yet another audience, sharing theirs. The NeverEnding Story, then, is not Atreyu's story, or Bastian's or even Fantasia's. It is the ever-spreading infinity of stories within stories being witnessed and shared. As such, it has no ending.
Bastian wishes back all of Fantasia at the end of the movie. That means he brought G'mork back to life.
Not so fast, I see it as that he only brought back the good parts of Fantasia. After all, why would he have The G'mork come back?
In the book, the G'mork states he is not a creature of Fantasia, but a being that can travel freely between worlds and take on a form which resembles the natives of any world. Restoring Fantasia did not bring back the G'mork because Fantasia did not spawn him to begin with.
Then again, there's the animated series that follows the events of the first two movies to think about. And guess who one of the main villains is?
