The Southern Air Temple - S1-E3
Other mistake: When the gang is in the Hall of Statues of Past Avatars, Katara points out the avatar cycle pattern of statues and Aang zeroes in on Roku's statue. The earthbender avatar statue next to Roku is of an unknown man with a sword, not Kiyoshi. (00:12:50 - 00:13:35)
Other mistake: It appears as if Steve is holding 3 $20 bills when he supposedly received $50.
Other mistake: In the voice cast list, the Groom's Father appears twice - with two different voice actors - and the Groom's Mother is not even listed.
Takishîdo wa kaze ni mau - S1-E1
Other mistake: Van and Lucky play a game where they draw cards in turn until someone finds the Joker. They draw a 4 of hearts, a 7 of spades, a 9 of diamonds, the ace of clubs. They were stacking the cards in two separate decks, each one to their own right, but in the rest of the scene all the discarded cards are tossed together in a heap, and the aforementioned cards, which should be on the bottom of it, are the ones who always appear in the various shots of the table at the top of the bunch.
Gopherville - S1-E1
Other mistake: In "Sock Safari", when Toopy finds a red thread, his left hand with his glove disappears instantly.