Violet knew of Beverly's intentions (Situational Irony)
The final climactic moment of the film revolves around a gross irony. Violet asks all of her children to come home to be with her while they look for Beverly. Ironically enough, however, it comes to light that Violet knew her husband had gone off and did nothing to prevent his suicide. She has feigned ignorance about the event for the entire play until she reveals to Barbara at the end that she knew about it before it happened, a devastating divulgence.
Brother Lover (Dramatic Irony)
Little Charles and Ivy are cousins that are in love with each other and they plan to move to New York City in order to get away from their family's judgment and live happily together. Partway through the play, Barbara learns from Mattie Fae that the two are actually brother and sister. She is tasked with telling her sister the devastating news, but holds off. Thus there is a period of time in the play in which we the audience know that Ivy is in an even more scandalous incestuous relationship than she knows before she does.
Steve (Situational Irony)
When we first meet Karen, she tells her sisters how intent she has always been on finding the perfect man, and believes she has found the perfect man in Steve. She discusses the fact that she's dated bad men in the past, but there's something different about her new relationship. Ironically enough, Steve turns out to be an especially disruptive and unethical fiancé; he works in some shady business in the Middle East and molests the 14-year-old Jean in the middle of the night. All the more ironically, even though Karen's fantasy is completely shattered by these events, she chooses to blame Jean and stay with Steve.
Like Mother (Situational Irony)
Barbara wants nothing to do with her mother and hasn't been home in several years because of the tension between them. She's moved to Boulder and begun a new life as a way of disengaging from her painful past. Ironically enough, after Bill leaves her, Barbara becomes more and more like Violet, staying in the house, drinking at all hours, and wearing a nightgown all day. She becomes her worst fear.
