The inclusion of Casa Bonita was based on the crew's memories of going there as children; Parker, co-creator Matt Stone, director Eric Stough, and other members of the show's staff had visited the restaurant before.
An irate Cartman denies ever having engaged in this behavior (followed by a montage of him calling Kyle a Jew) and decides to prove that he is actually nice, but since kindness is such a foreign concept to him, his first attempts are unsuccessful.
Cartman then takes advantage of the reason and subsequently tells Butters that a meteor is about to hit Earth and hides him in Stan's uncle Jimbo's bomb shelter so that he does not appear in time for the trip.
Butters' disappearance causes a town search party and several days later, the police announce that they will be checking more secluded areas, such as ducts, wells, and bomb shelters, potentially ruining Cartman's plan.
Cartman relocates Butters to a broken-down gas station and locks him in an abandoned refrigerator for his protection after pretending to get bitten by a radioactive cannibal.
Knowing that his entire plan failed, Cartman makes a mad dash through the restaurant to sample every attraction and food in the last minute of freedom he has left.
A police officer angrily explains the trouble Cartman has caused, noting that he made an entire town panic, he lost all his friends, and will be sent to juvenile hall for a week.
They received clearance from Casa Bonita to use their name and likeness, which Parker and co-creator Matt Stone thought was very unusual, making them "even cooler.
The show's animation director, Eric Stough, had also gone to Casa Bonita as a child, and other individuals on the crew from Kansas and New Mexico were familiar with the restaurant.
Of the hundred or so Google and Yelp reviews I've read about Casa Bonita, a solid half of them mentioned Cartman or South Park as their motivation for dining.
[13] "Casa Bonita", along with the fourteen other episodes from South Park's seventh season, were released on a three-disc DVD set in the United States on March 26, 2006.