Any character in a fairytale backstory, looking around at the surroundings: "I never should've given up the animation rights."

Iroh has been to the spirit world.
This is mentioned multiple times, I think, and particularly in the finale episodes of this season. It's implied that his having visited the spirit world has given him some kind of link that allows him to see things like spirit-Aang. Well, implied by the fact that he has been to the…