The band managed to play in some hole-in-the-wall bar under the guise of "The Good Ol' Boys." That is, they assumed the bar manager got their name wrong. After they leave, the real Good Ol' Boys show up; they played their gig and ganked their paycheck in the process (Too bad Jake forgot the first rule of playing a gig: "Never assume the drinks are on the house.")
The Good Ol' Boys shouldn't really complain about stealing the gig, they didn't show up until the bar was closing.
They also tore it up with their revue later on in the film.
Special CMOA points go to Cab Calloway for absolutely killing with "Minnie the Moocher".
Elwood's introduction to "Everybody Needs Somebody To Love" — there is something incredibly ballsy about not just acknowledging presence of the police officers who have arrived there to arrest you, but actually welcoming them:
Elwood: It's so nice to see so many of you lovely people here tonight, and we would especially like to welcome all the representatives of Illinois's law enforcement community that have chosen to join us here in the Palace Hotel Ballroom at this time...
The entire fourth quarter of the movie, which starts with this very famous exchange:
Elwood Blues: It's 106 miles to Chicago. We got a full tank of gas, half a packet of cigarettes, it's dark, and we're wearing sunglasses. Jake Blues: Hit it.
Playing Jailhouse Rock while they themselves are all in jail. Bittersweet, perhaps, but given the odyssey in getting to Chicago, which ended with them finally paying the county clerk to keep their old orphanage open, and every cop, firefighter, soldier, and National Guardsman within several states to bring them in, it was all worth it.
The overall tone is triumphant, though, considering how final scene plays out. The band doesn't let a little thing like prison change anything. No matter where they are, or what's happened, they will always be making music, and they will always get people dancing.
The soundtrack to both movies are musical CMoA in my opinion - If you can't tap your feet during the musical numbers there must be something wrong with you!
And considering the shear number of musical genres represented.
The awesomeness of all the awesomely awesome musicians they managed to get to perform should have caused some kind of world-imploding awesomeness singularity event.
Who could forget Carrie Fisher's epically badass speech to Jake?
Jake: It's good to see ya, sweetheart.
Carrie: You contemptible pig. I remained celibate for you. I stood in the back of a cathedral, waiting, in celibacy, for you, with three hundred friends and relatives in attendence. My uncle hired the best Romanian caterers in the state. To obtain the seven limousines for the wedding party, my father used up his last favor with Mad Pete Trullo. So for me, my mother, my grandmother, my father, my uncle, and for the common good.... I must now kill you and your brother.