Harsher in Hindsight: Zuko's assurance to Iroh that "We'll meet again" takes on a whole new meaning when we learn that Iroh said almost the exact same thing over his son's grave.
Inferred Holocaust: Aang claims to have taken out "dozens of Fire Navy ships." While they were a mile-ish out at sea. In freezing cold water. And that's not counting all the other waterbenders assaults on the Fire Navy, or the massive fire balls taking out large portions of the city. No deaths occur onscreen, but it's reasonable to assign this episode a fairly high body count.