Both Stan and Kyle's mothers are named Carol. However, for the rest of the show's history, Stan's mom is Sharon and Kyle's is Sheila.
After Stan's mother places the birthday cake on the table, it completely disappears after a couple of shots.
The end of the parents' crusade implies that Terence and Philip has been cancelled. Yet the show is still featured prominently in later seasons.
It's stated, distinctly, on many occasions here that Terence and Philip are "cartoons." But according to the movie and later seasons they are live-action actors.
Death chases the boys from left to right, but stops to watch the TV's at Tele's. The boys look over their right shoulders and go back. But instead of coming in from screen right to join Death, they come in from screen left.
Terrance and Phillip are from Canada but have USA flags on their space suits.
Kyle's mom calls Stan's mom "Carol", when handing her the phone.