Remember what Milo said in the beginning of the first movie? His intent for the expedition was to find Atlantis's power source and bring it back to the surface. And what happens at the end of this movie? Using the Spear of Destiny, Kida achieves just that: bringing the Heart of Atlantis (and by extent Atlantis itself) to the surface to share it. Talk about yourBook Ends!
Any person with some basic knowledge of Norse Mythology can agree that Hellstrom's view of Ragnarok is skewed, to say the least. He doesn't seem aware of the fact Odin would have been Eaten Alive by Fenrir (on the basis that he wants to create the world anew from the ashes of the old one). He also makes up or mixes legends which already exist, for that matter. Brunhild was indeed one of Odin's valkyries, but not his daughter. His spear Gungnir was never intended to trigger Ragnarok, its only magic power was to never miss its target. And he wears a winged helmet. These contradictions make sense if one recalls that, to begin with, Hellstrom was a madman with an Omnicidal Maniac complex and he lived in a time when the Wagnerian version of Norse mythology ran rampant.
Other mythical beings being real as well may explain why Atlantis was waging a war at least 8000 years ago, when all other known societies have just started using bronze. It could have been fighting other godlike entities for various reasons.
