Corrected entry: The daughter of Dr. Kane, Sol's sister, looks at the Bentley and says, "What does this do?" apparently clueless about cars and their use, yet as we later see, cars and other vehicles (buses, bikes, cabs, highway patrol cars) are used by the punks. Sol himself is seen driving a car.
Corrected entry: The survivors of Glasgow turned to cannibalism due to the lack of food. However, in one scene we see hundreds if not thousands of cows.
Correction: The cows were all seen near the barricaded border. Over time, the cows would have become feral. The Glaswegians probably never went as far as the border, as they learned from their parents and possibly first hand experience that anyone going too close to the border were killed by the guarding weapons. They soon wouldn't have any reason to go to the border, and may never have even known about the cows, as there were no cows around Glasgow. The population explosion of cows was also explained in the movie as having been a very recent development.
Corrected entry: Somehow, a Bentley Continental GT is still able to function perfectly, with no deflated tires, evaporated fuel or corroded components, despite being left in a cargo container for 27 years.
Correction: The car was being transported, that's why it was in the container. Some of the shipping containers are airtight, minimizing rust, corrosion etc. They are also shipped without fluid, so there would be no gas or oil to evaporate, which is also likely why she told the sergeant to "Fill 'er up". The tires should definitely be low or flat, though.
Correction: Sol's sister was raised in a medieval atmosphere before she was kidnapped and taken into the city. She likely arrived by the train, the same one used to escape the city. She may not have had any contact with a car. Sol, on the other hand, had voluntarily gone to the city in an act of rebellion, and became a leader of the city dwellers, so he would have learned about vehicles. Sol's sister may have heard vehicles in use while in her cell, but not seen any of them.
rswarrior