Hannibal and Count in Susan's Room (Dramatic Irony)
There is a great deal of dramatic irony in the first act of the play, in which both Hannibal and the count hide in Susan's room when Basil comes in. The audience knows that they are both there, but Basil has no idea. Additionally, the count has no idea that Hannibal is there. Thus there are multiple layers of dramatic irony operating at once.
The Count finding Hannibal (Situational Irony)
In this same scene, the count describes how earlier, he discovered Hannibal in Agnes' bedchambers. As he tells the story, pulling aside the countess' gown as a substitute for the curtain he drew in Agnes' room, he finds Hannibal. In the process of relaying a story about his discovery of Hannibal, he ironically discovers Hannibal yet again, in another place he ought not to be.
Susan takes Hannibal's place in the Dressing Room (Dramatic Irony)
When the count goes to get an instrument to force open the countess' dressing room door, suspicious that she is having an affair, she goes with him, worried about what he will do when he finds Hannibal inside. However, while they are out of the room, Susan lets Hannibal out of the dressing room and orders him to jump out the window. She then takes his place in the dressing room. When the count and countess return, the countess has no idea that Susan has taken Hannibal's place, but the audience does, creating another humorous instance of dramatic irony.
Figaro's Jealousy and the Count's Affair (Dramatic Irony)
The end of the play depicts a chaotic sequence of events that are made all the more chaotic by virtue of the fact that the audience knows certain key facts that characters do not. Susan and the countess trade clothes, so that the countess can pretend to be Susan and seduce the count, her husband. When he meets her in the garden, he has no idea that the woman he is with is, in fact, his much-neglected wife. This accounts for one part of the dramatic irony of the end. Additionally, Figaro believes that the countess is Susan also, and suspects that his wife is having an affair. He approaches the woman whom he believes to be the countess but is actually Susan and makes moves to seduce her. The audience knows that he is really just seducing his own wife, and that Susan was never unfaithful to him, but he wants to retaliate for this imagined affair.
