Raina's Room
The stage directions for the beginning of Act I reveal a lot about Raina. Her room is a clash of east and west styles, some gorgeous, some paltry. Her furniture is cheap but the furs she wears are expensive. The mix of high and low signifies the war between her true feelings and pretensions. Staring out at the mountain, she is "intensely conscious" of the vista's - and her own - beauty (2). Raina is romantic, but acutely aware that her romance is calculated. When Bluntschli storms into her room and life, she maintains her pretensions about love and war at first, but is taken over by empathy for his plight. In her room, Raina plays the full range of her feelings.
The Library
The stage direction for Act III begins with the reveal that the library is nothing more than a single shelf of books. This visual gag is also a symbol of the Petkoffs' pretenses of class. The shelf is shoddy, housing just a few stained, used paperbacks. It is quite the opposite of the grand library they tell all of Bulgaria about. In Act III, all of the preconceived notions and performances break apart into truth, and the library is the perfect visual to connote the disconnect between the Petkoffs' words and their true feelings.
Louka's bracelet
When Sergius bruises Louka's arm in Act II, her response in Act III is not to hide the marks with her dress, but to roll up her sleeve with a broach and wear a gilt bracelet. Even the way Louka saunters into the room is in defiance of her station. The jewelry is meant to be eye-catching; indeed, Nicola notices it and chastises her immediately. Louka's bracelet is a visual clue and a symbol of her brashness. She wants to wear her love for Sergius proudly on her sleeve, and will not allow fashion, custom, or class to change her behavior.