Audio problem: After Stan does the line dance while the other team announces that "its on", and the bystanders are watching. As the blonde haired white guy says "Oh Lord its on." The Asian kid from the group is saying the exact same thing. However you don't hear his voice.
Audio problem: Near the end of the episode, where the boys are standing at the bus stop and Kenny (who is in a seizure trance) starts getting attacked by rats, Cartman yells, "Hey, get away. He's not dead yet", but it doesn't sound like Cartman (the tone seems more high-pitched.).
Audio problem: The animated Christmas movie the boys are making is really "the Spirit of Christmas", the movie Trey Parker and Matt Stone made before South Park. The dialogue recorded by the boys is the same as in the original (with a few changes, but when the film is shown later it's the original speech from "The Spirit of Christmas". You can tell by the way the voices are done, and the tone of the voices.