The film's MPAA rating appears at the very end of the closing credits - as part of the regular scrolling credits rather than on the screen by itself. What is also unusual is the rating usually appears at the start of a film, not the end.
The ending credits scroll while Carmen and Juni are somehow set to perform before a crowd of teenagers. Carmen is nervous but their Uncle 'Machete' gives them gadgets so they can perform well in front of the crowd. Then the bloopers and goofing around sequences come in, followed by a sequence where the amusement park owner (Bill Paxton) tries to talk Romero (Steve Buscemi) into establishing a theme park on the island. Finally, the Treehouse is shown getting ready for visitors.