Other mistake: In the very first shot (a long tracking shot backstage), watch the girl practising with her tuba. At one point she pulls her mouth away and then leans back in and starts playing some notes. But you can tell that she isn't blowing into it, and in fact, her mouth isn't even quite touching it. So it shouldn't be producing any notes. Then, almost immediately after, you can also see the actress purposely moving the tuba (sort-of rotating it to her right) to get out of the cameraman's way.
Other mistake: Buffy freaks out when she's first taken to the hospital. Joyce tells the gang it was because her cousin died when they were young, but in season one episode "Angel" Buffy has no problem being in the hospital, same with later seasons.
Chosen answer: "So goes the nation" seems to have been used on many occasions, with various different US states in the "As .... goes" section. Most commonly it seems to be California that's considered to lead the way, but probably most other states have appeared in the lead role at some point or another. Other things have also been used - no less a person that Pope John Paul II said "As the family goes, so goes the nation...". The origin of the quote format is unclear - in US politics it goes back into the 19th century, when it was Maine that held the title spot, but, while no definitive origin is known, it seems highly likely that it goes back considerably further than that.
Tailkinker ★