When Aang goes to play with the children outside, he creates an air scooter and runs into a statue, this taken from the opening credits of the animated series.
There is a painting on display in Avatar Kyoshi's shrine depicting her battling Chin the Conqueror on the day Kyoshi Island was created as seen in "Avatar Day" (S2E5).
This episode combines elements from multiple episodes from the animated series: The Southern Air Temple (S1E3), The Warriors of Kyoshi (S1E4), Winter Solstice Part 2 Avatar Roku (S1E8), and The Avatar State (S2E1).