Among the plays parodied in the llama theater festival are 'Hamilton' (Llamaton), 'The Book of Mormon' (Book of Llama), 'Joseph and the Amazing Technicolor Dreamcoat/Llama,' 'Death of a Salesllama,' 'Annie Get Your Llama,' 'Hello Dolly Llama,' 'The Llama Producers' and, just barely visible to the left of the screen, 'Rollercoaster the Musical,' which is actually an episode of 'Phineas and Ferb.'
The song that plays while the llamas are running amok includes the lyrics, "Here's a llama, there's a llama, and another llama over there..." This is likely a reference to "The Llama Song," a popular flash video from 2004, which begins with the lyrics, "Here's a llama, there's a llama, and another little llama..."
If you pause at 17:45, during the scene with llamas stampeding through the football stadium, you can see one of the pistachio men getting tossed around by the stampeding llamas. This is before the sentient pistachios have been introduced.