The Orator is Mute (Situational Irony)
The entire play hinges upon the sharing of the old man's message. However, when the moment finally arrives, the orator he has chosen is actually deaf and mute. As such, he is physically unable to actually share the man's message. In this instance of situational irony, the man has chosen a person who is incapable of speech to provide the most meaningful recitation of his life.
The Guests Are Invisible (Dramatic Irony)
The guests is entirely invisible throughout the play. Though they are described as murmuring and coughing at the end, there are no other actors portraying them onstage throughout the play. The man and woman carry on one-sided conversations, swear fealty to unseen rulers, and seem packed in by a crowd of people. However, all the while, not a single person is seen. In this instance of dramatic irony, the man and woman appear anxious and excited over an invisible group of people.
The Man's Wife Acts as His Mother (Dramatic Irony)
Though they are married, the man and woman do not resemble a traditional heterosexual couple. Instead, the man's wife acts as more of a mother figure to him, coddling and complimenting him. He responds by sitting on her lap and using baby talk. It is later revealed that this may be the result of his problems with his parents when he was young. In this instance of dramatic irony, the old woman more closely resembles a mother than a wife, despite being married to the old man.
The Couple Dies (Situational Irony)
At the end of the play, the couple leaps out of their window to their deaths. Having decided that there is nothing left for him to accomplish, the man proclaims that he will leave this life to spend eternity with his devoted wife. They say their last goodbyes and jump, hitting the water below and dying. Had he not done this, he might have been able to salvage the failed speech. In this instance of situational irony, the man assumed his place in posterity was so secure that he ended his life, unaware that his final message would be unintelligible.
