There are various election signs that can be found in the game that read "Richard Grimes for Sheriff". This is a reference to the main character of The Walking Dead TV series, sheriff Rick Grimes.
Contributed by ISayWynaut
Xbox 360 Slim consoles, along with an Xbox 360 Controller, can be found within a number of houses throughout the game.
Contributed by ISayWynaut
In an office, you can see 4 posters for the American cities "Wichita", "Tallahassee", "Little Rock" and "Columbus". This may be a reference to the film "Zombieland", whom the four main characters in the movie are named after.
Contributed by DeerBoarDude
Behind a house there is a garden that has sunflowers and lawn mowers. This is a reference to Plants VS. Zombies. Also, there is one zombie that was killed by a lawnmower.
Contributed by Funland47