Discussion BreakingBad / TropesCToD

On "Breaking Bad: Tropes C to D" there is currently an entry under "Chekov's Gun" that states:

• Walter's gun, throughout all of Season 4. It is, however, used as a prominent prop in various scenes where its presence alone has either thematic or plot-relevant resonance. However, he doesn't actually use it until the end of the final episode.

But doesn't he use his 38-Snub revolver in S 4 E 13 episode "Face Off?" When the laundry elevator door opens, Walt appears from behind view and fires a gun to kill the henchman in the laundry elevator and the two guys holding Jesse hostage in the Superlab. I compared the camera shots of Walt holding the gun as he draws to fire and shortly after he drops it, to when he first buys the gun in S 4 E 2 "Thirty-Eight Snub". It appears to be the exact same gun he bought from Lawson; and if that is indeed the case, then the above entry quote is incorrect. Is there a way to verify this?

I removed * California Doubling:

• California Doubling is the reason the series is set in Albuquerque and not, as originally planned, Riverside, California. Moving the production to Albuquerque was cheaper and left more budget to put on screen, but would have restricted the cinematography to avoid incongruous geography. The easiest answer was simply to move the story and take advantage of the local surroundings.
• When you look out of any office building in Hannover, Germany, you are exceedingly unlikely to see an empty red desert. More probably it would be some green within a grey in grey office area.
• Also, the New Hampshire scenes in "Granite State" were filmed in the Sandia Mountains of New Mexico.
• Otherwise, averted - everything else you see was shot on location to the maximum extent.

In the very first shot, there is a Texas borders/logo on one of Lydia's office window. It's a multinational company. The DEA does not have jurisdiction in Germany. It's quite obvious from the show that Lydia lives in Texas, Jesse having to drive back 14 hours without stopping with the methylamine barrel he doesn't get because the HOUSTON, Texas office/warehouse she works at DEA's office put trackers on the barrels of methylamine. So no California Doubling, from the very first time we see Lydia alone in her office, it is indicated she is in Texas, her little logo saying she got a prize for Excellence in her work a little similar to what Mr Burns gives to Homer in the simpsons if I remember well.