AMC may have just confirmed The Walking Dead is set in the same universe as Breaking Bad. It's a VERY SMALL clue though.
In a recent episode, Madison and Qaletaqa entered the market and the song ‘Negro y Azul: The Ballad of Heisenberg‘ could be heard! The same song could be heard in Season 2 of Breaking Bad!
According the Digital Spy, it was done on purpose. "I tried to be subtle with it," said showrunner Dave Erickson. "As we were looking for pieces to incorporate into this world, it had the right vibe to it. It's a gentle nod of admiration and adoration to [Breaking Bad creator] Vince Gilligan."
Here's the Fear the Walking Dead scene. Listen closely!
And here's the song as featured on Breaking Bad: