Panel 3: Brendan is evilled by "Yuba". He said he drove through there once, and it was your typical midwestern nowheresville. Plus, it has such a cheesy name. "Go pound sand" is one of the phrases on an all-purpose motorist's message sign I have. We also spent some time recording messages for the "Click here to bite spot" webpage, which had a big imagemapped picture of spot that you could click on, and it was supposed to play different messages such as "Owie!" and "Don't bite my nice flannel!" depending on where you clicked. I think it was never finished, though.
Panel 4: Back then, I had no trouble keeping caught up on the diary during the trip (as opposed to now, when I simply take notes and then spend weeks after the trip doing the actual drawing), and when spot came to pick me up, she got to see this panel, hence her reaction in panel 5.