Audio problem: When Toph feels and hears the tank train coming for the first time, she says, "There's something coming toward us," as she runs out of her tent. She turns her head away from the camera after she says "There's," but for the time her mouth is visible, it is not moving as she is speaking. (00:03:11)
The Tales of Ba Sing Se - S2-E15
Continuity mistake: The Tale of Zuko: When Jin and Zuko are at the restaurant, some of the items on their table constantly disappear, reappear, and change position depending on the shot. (00:16:30)
The Tales of Ba Sing Se - S2-E15
Audio problem: The Tale of Toph and Katara: Right after the scene of Toph and Katara at the Fancy Lady Day Spa, as Toph says, "Well, that wasn't so bad. I'm not... I actually feel girly," her lip movements are out of sync. (00:02:34)
Answer: The pirates are from the episodes "The Waterbending Scroll" and "The Waterbending Master" (They're the ones Katara stole the scroll from). The traveling musicians are from "The Cave of Two Lovers. The prisoners of war likely refer to the Kyoshi Warriors, the men of the Southern Water Tribe, and possibly Bumi and the other citizens of Omashu.