The price of gas when Daryl, Tyreese, Michonne, and Bob are looking for transportation is 4.377 but the numbers are turned upside down. Upside it spells HELL backwards.
When Rick (Andrew Lincoln) and Carol (Melissa McBride) stumble upon the couple in the house, and after they explain themselves, right before the cutaway, Rick starts the '3 question' interrogation that has become a staple of his character.
Dollar General brand car cleaning products and accessories can be seen on display at the auto shop where Tyrese, Daryl, Bob, and Michonne look for a car battery.
At the veterinary school when faced with the choice to open the chained door or face the infected walkers, the group chooses the latter. When they go through the double doors, they leave them wide open allowing the infected to follow. The wise move would have been to close the outward swinging doors behind them to cover their escape since the Season 4 walkers would simply push futilely against the doors and be unable to pass.