Mr. Andrews' detectives never recognize Ellie (Dramatic Irony)
Ellie jumps off the side of her father's yacht and swims to shore with plans to take a night bus to New York. Her father immediately sends a group of detectives and assistants to get her. When they arrive at the bus depot, they see a woman who they suspect is Ellie, but dismiss the possibility that it could be her, believing that as a wealthy heiress, Ellie Andrews would never take the bus. The viewer knows that that is indeed Ellie Andrews and that she intends to take the bus, in spite of her wealth and her being accustomed to the "finer things." Then later, when they come to inspect Ellie and Peter's cabin, the detectives do not recognize Ellie again, in spite of her photograph being all over the papers. She and Peter pretend to be a combative country couple, and the detectives leave them alone. The viewer knows that it is Ellie, but the bumbling detectives never seem to figure it out.
Ellie is Better at Hitchhiking (Situational Irony)
Peter makes a big deal out of the fact that he is a good hitchhiker and knows exactly how to get a car to stop and give them a ride. He even goes so far as to say that he could write a book about hitchhiking. He tells Ellie about his hitchhiking abilities with a haughty hubris, but when he sticks his thumb out, no cars stop for them. When Ellie tries her hand at hitchhiking, she simply lifts up her skirt and a car immediately stops. While Peter thought that he was the expert in the scenario, Ellie completely ignores his hitchhiking advice, uses her feminine attributes to stop a car, and proves much more proficient than him, an ironic turn of events.
Ellie thinks that Peter has abandoned her at the motel (Dramatic Irony)
When Ellie is woken up by Zeke and his wife at the motel, she looks over at Peter's bed, realizes that he is gone, and assumes that he has abandoned her and does not return the love that she professed to him the night before. The viewer knows that Peter has gone to New York to submit a story about their love affair to his editor, collect $1000, and return before she wakes up so that he can propose. Thus, there is a discrepancy between what we know and what Ellie knows, creating a dramatic irony that drives the two lovers apart for a time. We know that Peter loves Ellie, but she does not.
"Just gotta get there before she wakes up!” (Dramatic Irony)
Ellie's misunderstanding of Peter's actions only creates another misunderstanding on his part. As he drives back to the motel where he left Ellie, Peter is overwhelmingly excited to propose, hooting, hollering and cheering about his romantic feelings to the workers on a passing train. He mutters to himself, "Just gotta get there before she wakes up," but we the viewers know that Ellie has already woken up and left the motel. Again, we know more than the characters, and their being "in the dark" about the situation creates misunderstanding on either side. Ellie believes that Peter doesn't love her and so returns to King Westley, and her return to King Westley signals to Peter that Ellie doesn't love him back.
