Ventidius' arrival (Dramatic Irony)
When Ventidius first arrives, he stands onstage when Antony enters. Antony delivers a soliloquy to himself all about how inconsolably sad he is, but does not notice Ventidius. This accounts for dramatic irony in which we know that Ventidius is onstage, but Antony has no idea he is there.
Dolabella and Cleopatra (Dramatic Irony)
When Dolabella visits Cleopatra to deliver the news that Antony is leaving her, the audience sees that Cleopatra attempts to seduce Dolabella in order to make Antony jealous, but then decides not to. Later, Ventidius, Octavia, and Alexas all tell Antony that his friend and his mistress are having an affair and he becomes incredibly angry. This is an instance of dramatic irony in which the audience knows that the seduction did not take place, but Antony believes that it did.
Octavia leaving Antony (Situational Irony)
After telling Antony that Cleopatra is having an affair with Dolabella, Ventidius and Octavia expect that this news will lead Antony to leave Cleopatra once and for all. However, his first response at hearing the news is to try and find a way for it not to be true and to defend Cleopatra. Seeing this, Octavia realizes that he still loves Cleopatra, so she leaves Antony once and for all. Ironically enough, an effort to lead Antony away from his mistress only proves just how attached to her he really is.
Alexas says Cleopatra killed herself (Dramatic Irony)
In an effort to distract Antony and prevent his own killing, Alexas devises a lie and tells Antony that Cleopatra killed herself. We know this to be false, but Antony believes it, and promptly falls on his sword, a final and tragic instance of dramatic irony.
