The name Sokka suggests for Lian's doll, "Pippinpaddleopsicopolis the Third," is the alias used by Aang ("Bonzu Pippinpaddleopsicopolis the Third") when the Aang Gang first try to enter Omashu in the animated series in Season 1 Episode 5, "The King of Omashu."
George Takei (the voice of Koh) appeared in season 1 episode 6 of Avatar: The Last Airbender (2005) as the Warden.
In the bar, when Zuko and Iroh are asking about waterbenders, the bar patrons tell stories about the Avatar. One of them is about an encounter with pirates, the other mentions canyon crawlers. Both of these were episodes of the animated series.
The name of this episode, "Spirited Away", is likely a reference to Spirited Away, a Studio Ghibli film where a girl named Chihiro is transported to the spirit world.
Randall Duck Kim (the voice of Wan Shi Tong) also appeared as Old Man in Temple in The Last Airbender (2010)