Obi-Wan's Use of the Force (Dramatic Irony)
Obi-Wan Kenobi uses the Force at several key moments to get Imperial representatives off his case. For instance, in Mos Eisley, a group of stormtroopers come over and want to see Luke's identification and examine the droids, but Obi-Wan uses the Force to convince them not to do so. In this moment, there is an ironic disconnect between the fact that we the viewer know what Obi-Wan is up to, but the stormtroopers have no idea, and fall victim to the Jedi mind trick.
Luke and Han Solo as Stormtroopers (Dramatic Irony)
Han Solo and Luke Skywalker are able to infiltrate the Death Star and rescue Princess Leia through their use of stolen stormtrooper uniforms. With these uniforms, which obscure their identity, they are able to navigate the Death Star with relative ease, because the other stormtroopers have no idea who is behind the masks and armor.
Solo owes Jabba the Hutt Money (Dramatic Irony)
When Luke and Obi-Wan offer Han Solo a sizable reward for helping them get to Alderaan, he agrees. Little do they know that a large motivating factor for Solo is not just money for his own personal use, but money he needs to repay a debt to the nefarious Jabba the Hutt.
Ben Kenobi Saves Luke from the Sand People (Situational Irony)
When Luke sees Princess Leia's message on R2, he learns that she is looking for someone named Obi-Wan Kenobi, and wonders if he is any relation to Ben Kenobi, a man that his uncle Owen says is just a "crazy old man," who lives in the hills of Tatooine. It is ironic that, in the moment when Luke is in the most peril with Sand People, it is Ben Kenobi who saves him. It is also ironic that Ben Kenobi, who Luke has thought was insane, is very sane and is the same man as Obi-Wan Kenobi, the very person that R2 and C-3PO are looking for.
