Now the prison, I wonder if that is where Randall's group is hiding out?
That hadn't occured to me. Not sure though. When they stopped because they were short on fuel, Rick said they had been driving for an hour on red. That leads me to think they may have covered quite a few miles. However, you have to think that Andrea and the new character, Michone, will eventually connect back up with the group. So, maybe it wasn't a huge distance.
Of course, television writers are notorious for making odd leaps in the interest of steering the story they way they want it to go.