Some differences from the comics:
I don't remember the zombies being able to climb fences. It also seemed to be implied that they didn't move very fast (in comparison to the half-run of some of the zombies in this episode).
Also, I think the sex (between the wife and the best friend) was just a one-time event that was revealed later in the storyline.
It's been a long time since I read the opening story arcs, so I could be wrong.