 Spacey loosely based Lester 's early " <unk> " deportment on Walter Matthau . During the film , Lester 's physique improves from flabby to toned ; Spacey worked out during filming to improve his body , but because Mendes shot the scenes out of chronological order , Spacey varied postures to portray the stages . Before filming , Mendes and Spacey analyzed Jack Lemmon 's performance in The Apartment ( 1960 ) , because Mendes wanted Spacey to emulate " the way [ Lemmon ] moved , the way he looked , the way he was in that office and the way he was an ordinary man and yet a special man " . Spacey 's voiceover is a throwback to Sunset Boulevard ( 1950 ) , which is also narrated in retrospect by a dead character . Mendes felt it evoked Lester 's — and the film 's — loneliness . Bening recalled women from her youth to inform her performance : " I used to babysit constantly . You 'd go to church and see how people present themselves on the outside , and then be inside their house and see the difference . " Bening and a hair stylist collaborated to create a " PTA president coif " hairstyle , and Mendes and production designer Naomi <unk> researched mail @-@ order catalogs to better establish Carolyn 's environment of a " spotless suburban manor " . To help Bening get into Carolyn 's mindset , Mendes gave her music that he believed Carolyn would like . He lent Bening the Bobby Darin version of the song " Don 't Rain on My Parade " , which she enjoyed and persuaded the director to include it for a scene in which Carolyn sings in her car . 
