Sokka's not happy about this.
Many people often mistake this cartoon as an anime program due to the artwork and the martial arts aspect with the touch of magic. If artwork is the case, then you can think Totally Spies and Team Galaxy as anime too! To those who still believe that Avatar: The Last Airbender is an anime program; here are some things you should see.
First the title card, in the title card, there are names of the creators are listed namely, created by Michael Dante DiMartino and Bryan Konietzko, a duo of Westerners not Japanese. Both are influenced by films directed by Hayao Miyazaki of Studio Ghibli and Bryan, was influenced by Cowboy Bebop. Heck, I saw some notable Bebop influences! Namely, Jet’s hair resembles Spike’s, Azula’s hair in some angle resembles Faye’s hair and Iroh’s beard in Book 1 resembles Jet Black’s beard. They raised the ante by naming the forest in the last battle of the show from the currency in the Cowboy Bebop universe.
Also they mentioned on one interview about Book 3 that some places from the Fire Nation are based on the places the two visited on Europe.
Here's a sample of one ending title card from one episode.
In case you noticed while watching the ending credits of most anime shows, you noticed this name, Dr. Movie and his Korean crew which is responsible in doing animation for anime, most notably, Naruto and Bleach. Because of this, most people who didn't do their research justifies that Avatar: The Last Airbender is an anime. Here's the reason why Dr. Movie and co. are in the show. In one interview, the creators decided to use a Korean animation studio for the show since doing animation in Korea is cheaper compared to the US.