Jet contrails
I am watching this GREAT movie for the umpteenth time and just saw something strange.
When Brad comes to the crossroads where George is directing traffic, he has to tell him that he has to cut off his supplies, including gasoline. They continue the conversation and, if you look into the sky past them, you will see a long jet contrail. Jets were not flying at that time, they were still in the development stage and not able to fly that high to make a contrail like that.
It's amazing what you may have missed and now can see.