Rita presumably attended the Klara and the Sun premiere because her husband, Taika Waititi, directed it. Some people might say that being somebody's plus-one at a work function calls for more subdued clothes, but not Rita. Never Rita. And good on her; don't dim your crazy light for anyone, pal. Besides which, Taika seems like someone who would not only be DELIGHTED by her showing up in a hat that makes her look like she's at Royal Ascot on Maleficent Day, but in fact PREFER it that way. They really might be soulmates.
Also: a surprise Florence Pugh appearance!