No Spoilers as it's just my personal theory and I have seen no one else with the same one so here goes...
It's just something I picked up on when playing through episode 4.
As we all know at the end of episode 3 we had the train being followed by thousands of walkers, and as anyone who reads the comics or watches the Tv show will know, the herd gathers in numbers as it follows people or goes in the direction a loud sound is heard, even after the sound is gone they continue in that direction mindlessly walking.
During Episode 4 when you are escaping the bell tower in Crawford, Vernon says 'Did you guys come into town along the train lines?'
My theory is that the massive herd will make it's way into town during the final parts of episode 5, and the last few scenes could even be the group getting on the boat and driving off while Lee stands back at the docks.
Maybe.... just my theory anyway, I could be reading to deep into it but then again I might be right!