Dinah makes a comment about Diana covering her "Rumpus McGoo" (so to speak) with the American flag; Diana retorts that it's typical nationalism to assume that just because it looks like the American flag, therefore it must be.
This is interesting especially in light of the Wonder Woman costume controversy that's not quite yet hit us collections readers yet. New writer J. Michael Straczynski notes to Comics Alliance that he wanted Wonder Woman in a costume less sexualized and more idealized, which is a fair enough goal except that he also said to DC's Source blog "What woman only wears one outfit for 70 years? ... How does she fight in that thing?"
The answer to Straczynski's question, as I inuit it from Simone's panel, is this: the costume is not for you. To say, "How does she fight in that thing?" is to translate Wonder Woman's costume like Batman's costume -- something the hero built themselves for the purpose of fighting crime. But, Wonder Woman isn't Batman, and her "outfit" isn't a costume at all, really, but actually an Amazonian cultural symbol of their representative to Man's World. To some extent it's like asking how the Pope has worn that outfit for all these years -- it's not an outfit, but rather the vestments of the office.
Except, of course, that it's not.
In as dear as I find the tapestry of the DC Universe, we must avoid the temptation to mistake mythology for fact. Simone's Diana scolds us for mistaking her costume's resemblance to the American flag -- but at the point of creation, Wonder Woman's costume was indeed meant to symbolize the American flag; Black Canary may be generalizing, but she's not wrong. While it may be empowering for Wonder Woman's costume to be retroactively designated as an Amazonian vestment and not a bathing suit, when it was designed a bathing suit was likely what was in mind.