The makeup team on the movie tried to paint Noah Hathaway green, just as Atreyu is in the book. "It wasn't believable. I looked like fungi!" Hathaway said.
In the wide shot from 50:53 to 50:57 on the DVD where Atreyu scales the mountain to look through the telescope at the first oracle, you can see a horizontal line where the set wall (lighter blue) and ceiling (darker blue) meet. Basically, you can see that they are in a room instead of out in the desert.
G'mork: If you come any closer, I will rip you to shreds.
Atreyu: That's not true! You're lying.
G'mork: Because people who have no hopes are easy to control; and whoever has the control... has the power!
Atreyu: Who are you, really?
G'mork: I am the servant of the power behind the Nothing. I was sent to kill the only one who could have stopped the Nothing. I lost him in the Swamps of Sadness. His name... was Atreyu.
Atreyu: If we're about to die anyway, I'd rather die fighting! Come for me, G'mork! *I* am Atreyu!
G'mork: I am G'mork. And you, whoever you are, can have the honor of being my last victim.
Atreyu: I will not die easily. I am a warrior!
G'mork: Ha! Brave warrior, then fight the Nothing.
Atreyu: But I can't! I can't get beyond the boundaries of Fantasia!
Atreyu: What's so funny about that?
G'mork: Fantasia has no boundaries.