In the summer of 1981, the Grateful Dead did play nine shows in a week and a half, starting at The Summit in Houston, Texas and finishing up at McNichols Arena in Denver, Colorado exactly as Laurie stated to Lindsay when describing her summer plans.
The trivia items below may give away important plot points.
During the episode, Lindsay has trouble deciding if she wants to attend the Academic Summit at the University of Michigan. However, she decides not to go to the Academic Summit and decides to go on the road with her friends to follow the Grateful Dead. Laurie mentions that the first show is Texas. Coincidentally, the show actually took place at a place called The Summit in Houston, Texas.
Lindsey drives off in a "Dead Head" van with a picture of the "Cosmic Cutie" from 'The Hitchhiker's Guide to the Galaxy' painted on the side with the words "Stay calm", a play on the Guide's catchphrase: "Don't panic."
When Mr Rosso is talking to Lindsay about the academic summit he quotes The Grateful Dead. The quote is from the song Box of Rain, released in 1970. It's the first song on the album American Beauty, the album Mr Rosso lent her.