What I especially wonder is if it’s realistic for us to expect that Emmett and Billy were able to escape any consequences from the law. If the authorities had found the canoe, Duchess’ body, and/or any of his cash, that would look suspicious. Then they might have searched for and found Emmett’s fingerprints. Maybe the author wanted us to wonder about these things.
Of course, we also never find out whether the Watson brothers find their mom, but I have to believe that they never do. Even if they were all attending the San Fran 4th of July celebration, it would be near miraculous for them to find her among the thousands of other people there. I do, however, want to believe that Emmett and Sally end up as a couple and think that’s much more likely than them finding their mom.
I think it being the less technological 1950’s led to its credibility. With fingerprinting data bases and DNA analysis and facial recognition and so much technology today, they would doubtless be caught. Maybe that is part of the charm of the decades challenge: one can go back to a less technological world and wonder how things might have been. In this case it is how our antiheroes might have escaped.