Continuity mistake: Atreyu rests by a stream and his horse walks over to nuzzle against him. The horse does not have a proper girdle to hold the saddle on. Later, when he's riding across the sandy desert, the horse does have a broad girdle.
Continuity mistake: Atreyu gets a spot of mud under his right eye after losing his horse in the swamp. In the subsequent scenes, there is a (different) blob of mud on his face, and it changes size from shot to shot.
Continuity mistake: Atreyu climbs up a tree and talks to the Ancient One. There is a series of face-on shots of the boy alternating with ones from behind him. In the face shots, Atreyu's left hand is below shoulder height on a branch. In the shots from behind, his left hand is holding the branch well above head height.
Continuity mistake: After Hathaway leaves Rockbiter, a large wall of rocks is not there.
Continuity mistake: When the warrior in armour is knocked down by the rays that the Sphinxes shoot, the warriors shield and sword move their position between shots. The shield reverses and the sword moves closer to his body.
Continuity mistake: When Atreyu is washed up on the beach, his chest is covered in sand. He stands up, and suddenly all the sand has disappeared.
Continuity mistake: When Atreyu first sets out on his quest, his horse Artax is grey with dark mane and tail. However, when they stop to rest and eat by the stream, Artax is white with white mane and tail. By the end of the film, when Bastian and Falkor flies over Fantasia,they spot Atreyu and Artax - low and behold - Artax's mane and tail are dark again.
Continuity mistake: When Atreyu and Artax set out on their quest, the Ivory Tower in the background is reversed.
Answer: Atreau is the main character of the book (like Bastion is to us watching the movie) this makes them the same, the main protagonist or the "story" It's a 4th wall break inside a 4th wall break. The Empress even tells him "he is sharing all your adventures, others are sharing his."