These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Everyone Is Jesus in Purgatory: The fact that the line "carrying the fire" appears here and in No Country For Old Men hasn't gone unnoticed. One theory has it that The Road is a distant sequel to Old Men. Another theory is that everyone really is in Purgatory and that the boy is their savior.
Inferred Holocaust: Pretty much one of the reasons why the ending is so bittersweet. Even though the boy is in good hands, the biosphere may be dead. If so, no one is going to live long once what is left of food is eaten and the remaining humans have all cannibalized each other.
Moral Event Horizon: In a rare example, the protagonist does this, stripping the thief down to nothing and sending him off to die a long, cold death in the process.
Nightmare Fuel: Lightning-struck man with a melted face sitting on the road and waiting to die.
The protagonist and his son enter a house, and the son keeps saying he doesn't want to go in. Then he opens a door and finds the people the bad guys have been eating...alive.
The protagonist later sees three men and a very pregnant woman. Three days after, he and his son pass through a camp that has the remains of a beheaded, roasted infant on a spit.
Sci-Fi Ghetto: If you value your life, don't bring this book up in front of longtime science fiction fans.