Plot hole: When Scott Tenorman shows the other kids a video of Cartman doing his "piggy" act, the angle of the video shot shows that it could only have been taken from the place where Scott was standing when Cartman originally did it - but Scott is seen at that time to have no video camera or any way to have recorded this.
Plot hole: How was Cartman able to afford a fairly lengthy TV ad, when he had already spent all his money on the theme park? Cartman took all his money with him to buy the theme park. After buying the park, he runs the TV ad mocking Stan and Kyle. Soon after, when he hires the security guard, he reiterates that he had spent all his money to purchase the theme park. Cartman would not be able to get a loan (he is too young), even as a co-signer. Cartman's mother is also not wealthy enough to give him the money.