The Car (symbol)
The automobile has long been a powerful symbol of manhood and masculinity. Mitty’s imagined adventures mostly take place while he is in his car and are undermined by this wife’s intrusions into that fantasy world. Then there is the real-life engagement with the parking lot attendant that also undermines his masculinity. Thus the car—and his failure to correctly pilot it—becomes a symbol of emasculation for Walter in his real life.
The Overshoes (symbol)
Mrs. Mitty's domineering insistence on Walter getting and wearing those overshoes is a concrete indication of his sense of being belittled and controlled by her. Her insistence on his wearing overshoes, which protect shoes from getting dirty or wet, specifically suggests that she thinks he needs to be protected from the influence of the outside world.
The Imaginary Sling (symbol)
Walter’s imaginary sling, which would excuse his lack of skill in car repair as compared to the parking lot attendant's abilities, becomes a symbol of Walter's need for an imaginary support to excuse his real-life sense of inadequacy. The sling itself represents a failure of motor skills, but the additional layer of the sling not even being real further indicates the point to which Walter has lapsed into his fantasy world.
Mitty's mutterings to himself (motif)
Although most of Mitty's daydreaming goes on silently, in his own head, and therefore remains there, sometimes a word or two (such as "puppy biscuit") escapes his lips and, like most of the things he does in actuality, brings him some embarrassment. Mitty's imagination might be impressive, dramatic, and overwhelmingly masculine, but his slips of the tongue demonstrate the futility of any attempt to translate this internal reality to the outer world.
Beautiful women (motif)
The frequent and in a sense necessary occurrence of beautiful women in Mitty's fantasies is both a part of the overall picture of masculinity his persona embodies in each dream, and a direct negation of the actual woman in his life: a wife who inspires little passion (or self-confidence) in him, and much shame.
