Walter loves Cheryl (Dramatic Irony)
A major dramatic irony that occurs throughout the film is Walter's love for Cheryl. The first scene of the film is Walter agonizing over whether to send Cheryl a "wink" on a dating website, and this sets the scene for his admiration for her that persists throughout the film. She is unaware of his affection until the end, leading to extended dramatic irony.
The Negative is Missing (Dramatic Irony)
Walter tells Ted that he has the negative for the final cover of Life magazine, even though he does not actually have it. He leads people in the office to believe that he has the picture even though the viewer knows he does not. The plot of the movie is built around his locating the negative without the powers that be finding out that it's missing.
Walter's skateboarding (Dramatic Irony)
In the park, Walter meets Cheryl's son, Rich, and shows him a number of impressive tricks on his skateboard. While he does the tricks, Cheryl looks away, and when she turns back to look at him, he has stopped doing the trick. This creates a comic instance of dramatic irony in which the viewer sees an impressive thing that Walter is doing, while Cheryl just misses it every time.
The negative is in the wallet (Situational Irony)
After traveling all the way to Afghanistan (through Yemen), and hiking through the Himalayas alone, Walter asks Sean where negative 25 is, and Sean tells him it has been in the wallet he sent all along. Making matters all the more ironic is the fact that Walter has thrown the wallet away and believes that it is lost forever.
