"We Blew It"...
"After George's murder, the film becomes increasingly dark in mood, develping a bitter tone of disenchanment. It is as though the oppressive conventions of stable society are ultimately inescapable, contaminating their easy riding [...]."(Laderman, 76)
When Wyatt tells Billy "we blew it", I believe he is making a statement about their direct situation which would entail himself and Billy; however, as films will, they often carry another message behind what is said. "We blew it" could also be used to portray the other young men, and possibly women, who were also part of the sub-American culture of the late 1960's.
Wyatt's statement in the film shows his disappointment in relation to their trip but it also foreshadows the final moments of the journey. Wyatt and Billy do not return home (to where ever that might be, as the movie is about finding their own America and creating their own home) and they do not survive the journey. The statement could be thought of as a precursor to what is to come in the following decade.