The most significant narrative technique that is used in this excellent story is that of parody, which is a work that ridicules another work or genre by imitating some aspect of its style or content. If you read carefully, you will see that the day dreams to which Walter Mitty is so susceptible are actually clever parodies of various film genres which allow Walter Mitty to gain the respect, power and prestige that he obviously does not possess in life. Let us consider the first day dream which opens the story. Here, the commander that Mitty imagines himself to be has to go through a massive storm. It is a desperate situation with his Lieutenant advising him that what he is about to do is impossible. In addition, the Commander has a voice that is "like thin ice breaking." He has a white cap that is "rakishly" pulled over "one cold grey eye." He is a Commander who inspires confidence in his men. Clearly this is something out of a film that Mitty has watched and been attracted by.
Let us not ignore the impact of the juxtaposition of Mitty's dream life with his real life. The reality of his existence, featuring a domineering wife who oppresses him, clearly reveals why he feels the need to live more in day dreams than in reality. This is shown when the day dream and reality collide and Mitty, caught up in his dream of accelrating the plane through the centre of the storm, actually speeds up the car he is in.