The reaction has begun... ~Walter White
Adam Rifkin stashed this in Breaking Bad
...And there's no going back... ~Heisenberg
Wow, can't believe I didn't make that connection. And they put this scene right in the middle of the gunfight, so it alludes not only to the overall story arc of Walt, but also specifically to the gunfight, and Walt calling Uncle Jack for back-up. The reaction has begun, there's no calling back Uncle Jack; Hank and Gomez are going to die.