The Prologue is full of fourth wall breaking. From the cast acknowledging how complicated their names are, to Mary, Bolkonsky, and Balaga being explicitly labeled as "Minor characters", to Mary and Bolkonsky bluntly stating:
Andrey's family, totally messed up.
In "The Opera", the ensemble pities Pierre for being home alone while Helene and Dolokhov attend the opera together. Pierre denies it, sounding annoyed and flustered in the process.
Ensemble: "Pierre the cuckold sits at home! Pierre the cuckold sits at home! The poor man!"
Pierre: "No, I'm enjoying myself at home this evening!"
In "Letters," Anatole marvels over the love letter he just sent to Natasha. Then Dolokhov informs ushe's the one that wrote it. On the soundtrack, he sounds hilariously annoyed.
Sonya showing Natasha how she can allegedly see her future in the mirror, saying, "You'll see a coffin, or a man," before dryly adding, "Everyone sees a man."
In "A Call To Pierre", and despite the seriousness of the situation, Pierre (who is still quite hung over from "The Abduction") reacts to Marya's news about the botched elopement with more and more confusion and outrage, literally saying nothing but "What?" four times in a row.
