The episode moves some months forward in time after the last episode, visible in Gus's and Mike's operation with the German workers, Hector's recovery and in Kim finally removing her arm cast. Jimmy's PPD paperwork is shown to progress from June 2003 through January 2004 during the opening montage.
The time of the episode is established: January 2004. That places it 4 years before the beginning of Breaking Bad (2008).
Werner tells Mike his name, Ehrmantraut, translates to "world strength" in German, but it actually translates to "trusted dear."
"Big Rock Candy Mountain" was originally about the terrible life of a young homeless boy.