12th Street Riots Allegory
The film is not so much allegorical as based on real life, but it is allegorical in that it focuses on specific characters and their experiences at the time. Their experiences allegorize the experiences of the people involved in the riots as a whole, in that there are many different points of view in the movie, just as there were at the actual event.
Musician Symbol
Larry Reed and the rest of his band have a legitimate shot of making it in the music business. In fact, years after the riots, they do actually get a recording contract and become successful. However, Larry is not part of the group at this time. For him, performing as a group forever symbolizes the riots, and the loss of his bodyguard, Temple.
National Guard Symbol
To Dismukes, the National Guard represents authority and stature; this is why his is keen to ingratiate himself with them. They also symbolize honor, and he feels far more comfortable aligning himself with them than he does with the police.
Presence of the National Guard
The presence of the National Guard symbolizes the crossing of the line between a protest and a riot, and symbolizes the fact that events have become completely out of control.
One Bad Apple Motif
Krauss is not representative of the police department at all, but he is evidence of the principle that one bad apple makes the entire barrel bad - or at least, makes them appear to be that way. When you consider how many police officers were present that day, Krauss is not symbolic of their behavior or their actions at all, yet to those involved, and particularly the witnesses to and the victims of his complete lawlessness, he is entirely symbolic of the police department.