Fridge BrillianceandFridge Horror: Roger, in "Black Jack" says he saw, in the sky, a bright light with a ring around it, and it inspired him to keep going. The very same nuke that caused the EMP and drastically lowered the standard of living for millions was what kept Roger alive, in a weird sort of way.
Fridge Brilliance: After the destruction of Denver, the people of Jericho are unsure if it was an accident or a deliberate attack. Then Dale plays his mother's final answering machine message, revealing that Atlanta was also destroyed, and confirms it was deliberate. I later realized that this was a parallel with the 9/11 attacks. After the plane hit the first tower, there was confusion over whether it was an accidental plane crash or a deliberate attack. Then the second tower was hit...
In "Red Flag", China airdrops supplies from old Vietnam War-era planes. The characters wonder why China is using 1970's equipment. It makes sense if China was also hit by an EMP: Soviet avionics always used vacuum tubes, so they won't short out in an EMP like modern computers.
It makes sense even without an EMP: China's military lags behind technologically in many regards. They actually use '70s era transport planes, and even designs older than that.
Fridge Horror: April dies due to complications from pregnancy. How many more pregnant women in town also died that winter because they had no medicine, lacked central heating, from disease and stress. Of course, that's not to mention the number of pregnant women in the entire country who died because the United States was nuked back to the 18th century.
Fridge Logic: An ultrasound machine manages to survive the EMP simply because it was in the hospital basement? That's some Ragnarok-Proofing right there, as it was a regular concrete basement.