Harry's Paranoia (Situational Irony)
A central irony of the film is Harry's personal relationship to surveillance. While Harry is a surveillance expert—"the best bar none," as Bernie says—he is exceedingly paranoid about being surveilled himself. He has three locks on the door to his apartment, a burglar alarm, and calls the woman at the front desk to give her an extensive lecture on how he wants to be the only person with access to his apartment. For someone who is so good at insinuating himself into the private affairs of others, he has a rather paranoid relationship to his own privacy. In fact, the tight hold that Harry has on his private affairs is so all-consuming, that it prevents him from having a personal life.
The Director's Death (Situational Irony)
While Harry believes that Ann's life is in danger, worrying that the director will kill her when he gets proof that she is having an affair, at the end of the movie we discover that it was actually Ann and Mark who killed the director. Harry's expectation was that he could save the life of the two lovers, but instead, they were the murderers. This reversal becomes the twist ending of the film. The people who seemed like the victims become the perpetrators, completely subverting both Harry's and the audience's expectations.
Meredith Steals the Tapes (Situational Irony)
Harry keeps a very tight hold on his life and on the all-important tapes. He becomes angry and paranoid when Stan begins to tell Bernie and the other people about the tapes, urging him to stop. However, that night, he is seduced by Meredith and allows her to spend the night with him at the office. Harry does not suspect that Meredith has any ulterior motives whatsoever, and plays the tapes obsessively before they go to bed. When he awakens, Meredith has stolen the tapes, and they get back into the director's hands. The irony is that while Harry is so careful, he allows himself to fall under the spell of Meredith, a femme fatale who ends up stealing from him.
Harry Gets in too Deep (Situational Irony)
Over the phone, Martin Stett urges Harry that the tapes have nothing to do with him and that he should just do his job—an urging that mirrors Harry's own advice to Stan in the office. Counter to Martin's warning, however, Harry gets more and more involved in the implications of the tapes, anxious that something unethical will happen because of them and because of his work. Harry is desperate to know what will happen if the tapes get into the wrong hands, which ultimately leads him to follow Ann, Mark, and the director to the hotel. Ironically enough, Harry ends up seeing and hearing too much, which makes him a suspicious witness in the eyes of the corporation, who have bugged Harry's apartment and are keeping close tabs on him. Thus, Harry's desire to prevent his own possible implication in a murder has in fact entwined him in one. Harry's ethical idealism only compromises his safety and privacy. This irony leaves us with the tragic final image: Harry alone in his apartment, surveilled and unable to find the surveillance devices in his decimated apartment.
