In the first scene in the episode, Kyle refers to Scott Tenorman as a "9th grader". Then, in the middle of the episode when Cartman has everyone in his basement, Kyle refers to him as an "8th grader" that sold Cartman the pubes.
When Cartman notices Scott has left the Radiohead interview, four other kids have also disappeared - a 6th grader and three 4th graders. Two 4th graders - a brown haired kid and the one with a blue hat - reappear in time for the "Pube Boy" presentation.
The brown haired kid can later be seen behind and to the right of Kenny, nowhere near Cartman or the kid with the blue hat.
Also during the crowd scene during "Pube Boy", a 4th grader can be seen hovering in mid-air to the right of Bradley, Bebe and Clyde.
Tenorman would have found it difficult to film Cartman doing the "I'm a little piggy" thing without any camera, but he could of had a really small camera.
When Scott tricks Cartman by giving him the pubes and taking his $ 6.12, the end result should have been different; Cartman should have ended with more than just the pubes.
Scott's voice changes alot half way through the conversation about chillie. However, it was when he was crying, so it may just be it changes that much when he cries.