5x15: Granite State

Observations: “Jesse reaching for the grate (symbolically, reaching for the starlit sky) resembles the scene where he climbs the ladder to kill the mighty fly once and for all in 3x10, both visually and even to an extent thematically if you consider the notion of choices and their consequences which was heavily present in the aforementioned episode and subliminally implied in this one.”
Aria Mohtadi’s Breaking Bad Observations

3x10: Fly

Observations: “'A fly in the ointment’ is a saying which captures a running motif in Walt’s life. When he is overwhelmed by his situation he focuses on a small imperfection that he can obsess on instead. When he received his cancer diagnosis (1x01) he responded to the doctor’s dire warning by pointing out a mustard stain on his shirt. Recently we have seen him spend time cutting sandwiches (3x06), skimming pools (3x02) or fixing tables (3x07). Now apparently he wishes he was dead and not having to fret over being under threat from Gus so he fixates on the fly.
Robin Pierson’s review of 3x10

3x10: Fly

Observations: “There’s no end in sight, as Walt states in response to Jesse’s concern about Walt’s health. Walt reassures him that his cancer is still in remission, and therefore there’s no end in sight. This remark, however, speaks more to Walt’s inner turmoil rather than his health prognosis. Here lies the crux of the matter: Walt has turned to cooking meth for a ‘good’ and ‘moral’ purpose, to take care of his family. What more can a good man do in his life than provide for his wife and children, especially after he’s gone? However, with no end in sight, there’s now a ‘fly in the ointment,’ a contaminant in the laboratory of Walt’s own experimentation. His well-laid plans are suddenly tainted; they’ve outgrown their usefulness; the perfectionist’s plans are no longer perfect. Walt is still alive, cooking meth, and for what? To what end do his plans bring him and his family?“
– From  Eileen Kim’s answer to: Why is Walt obsessed about the fly in his lab? on Quora


3x10: Fly

Props: 18 realistic flies created for this episode by Graham Owen in Burbank, CA. Some of these flies had internal hooks, to allow for filming secured to a surface, with air moving the body and wings. Breaking Bad commissioned 10 more flies, embedded in crystal clear Lucite blocks, to be presented as gifts to the shows writers and producers. Each block has BB laser etched on one side.