Avatar Day - S2-E5
Continuity mistake: When we first see Aang in the stocks, Sokka advises him to use his Airbending to escape and begins "imitating" Aang's kata. During one pose, we see Sokka is wearing the boomerang, or at least the sheath it was in, that he had to leave behind at the beginning of the episode. He wasn't wearing it before, isn't wearing it after, and doesn't actually get it back until the climax. (00:02:09 - 00:06:33)