The narrative of Breaking Bad had a habit of pacing itself on leisurely strolls, but they gradually lead to something far darker than initially expected. There were a number of moments that shocked viewers, both with the suddenness of their occurrence as well as the cold-bloodedness of the characters involved.
In the end, though, the series' scenes cannot be viewed independently from the overall storyline, because they have been measured in such a way as to produce the maximum emotional impact. Nevertheless, there are some that stand out clearer than the rest, if only for the utter audacity they display.
Flynn's Reaction To His Long-Lost Dad
Flynn, who prefers not to use his birth name, Walter, Jr. anymore, receives a call from his dad who has been in hiding on the other side of the country. He asks his son if he and his mother require any money for their expenses, except the boy is even more furious than before.
Flynn screams at him, blaming him for Hank Schrader's death, finally telling him to "just die already!" Watching this softspoken person morph into a force of nature is amazing, but it also signifies that he will never be the same again, that the darkness created by Walter will forever be a part of his life.
Todd's Point-Blank Murder
Todd is taken along by Jesse, Mike, and Walt to capture a trainload of methylamine, for obvious reasons. The plan is a monumental success, even though the group faces some rather nerve-racking odds, and they are all pretty cheerful by the end.
That is until an innocent child accidentally comes across them. Todd decides to take matters into his own hands and kills Drew without hesitation. The others are horrified, but certainly not as much as the audience, who aren't used to such cold-blooded murders.
Walt Takes Out Mike
This had been coming for a long time, but it's still quite a shock when it happens. Walt expects some crucial information, but Mike refuses, claiming that everything bad that has happened is because of him.
They have a verbal altercation, following which the older man makes his way to the vehicle, presumably to return home to his granddaughter. However, this is not to be, because an irate Walter shoots him in the belly. He then tries saying sorry, but Mike would rather just "die in peace."
Jesse Is Forced To Commit Murder
Walt informs Jesse that the only way to protect themselves from Gus would be to end the competition, so to speak. He pressures his ex-student into shooting and killing Gale Boetticher, an excellent chemist they suspect is being primed to replace them as the R&D part of Gus' operation.
The series of events leading to his death are of domestic bliss — Gale listening to music while preparing tea for himself when his would-be assassin arrives. It's clear that Jesse is suffering greatly from having to go down this path, and it gets so much more morbid when he pulls the trigger.
The Plane Collision
After Walter's indirect role in Jane's death, her father's lack of attention during his job results in a devastating catastrophe: the collision between two planes in the skies of Albuquerque (and metaphorically aimed at Walter and Skyler's home.)
The accident is painful for everyone in the city, given that 167 lives were cut short. Such airline disasters are rare by themselves, and the unexpectedness of the moment adds a ton to the scene.
Walt Blames Hank For Everything
To avoid being arrested and imprisoned by his brother-in-law, Walt attempts to redirect attention towards Hank by devising a cunningly malicious plan. He appears on camera, in which his monologue pretty much establishes the DEA agent as the real methamphetamine puppet master.
The descriptions that the original Heisenberg provides make it nearly impossible to be disproved, which puts the Schrader family in an uncomfortable bind. The worst thing is that Walt had only recently been on such cordial terms with Hank.
The Prison Massacre
Gus' remaining associates, locked up in prison, meet a grisly fate at the hands of Jack Welker and his gang (of course at the behest of Walter White, who intends to terminate his previous employer's enterprise completely.)
The individual murders themselves are supremely macabre: everything from being violently stabbed to being asphyxiated to an agonizing death by fire. Ten prisoners, spread out over three separate jails, perish within the span of two minutes.
Hank Realizes Who The Mastermind Is
The viewers have always known the identity of Heisenberg, but they have also been able to relate to Hank's own journey into the case that defines his career. As such, when the DEA agent sits down at his in-law's guest toilet, he is completely clueless until he finds Walt Whitman's Leaves of Grass lying in a pile of restroom reading material.
The first page shows two sets of initials, "G.B." and "W.W." and a dark cloud almost instantly passes over Hank's face. The future is finally his to control, but nobody knows the direction he's going to take it in at this point.
Walter Leaves Jane To Asphyxiate
Jesse and Jane take drugs together, which angers Walt because it severely impacts their dealings. She figures out the best way to extract her boyfriend's cut of the profits from his partner is by threatening him, which does not work out in her favor, unfortunately.
When the couple is unconscious after getting high, Walter accidentally moves Jane into a supine position, when she pukes and starts choking on it. There is a brief pause during which it seems like he's about to help her, but then he opts to let her die, knowing that this would drive Jesse back into his arms.
Walter, Ricin, And Brock Cantillo
Brock Cantillo, the son of Jesse's new girlfriend, suddenly becomes horribly sick, and Jesse suspects that Walt is behind it (when the ricin-cigarette vanishes from his possession). When he confronts his partner, the latter vehemently denies having been involved, instead shifting the blame to Gus.
Brock's medical team assure Jesse that ricin hadn't been the cause, but that he had "accidentally" consumed the toxic fruits of the lily of the valley. But when the camera deliberately moves into Walt's backyard, it pauses on a potted plant, clearly the same one that Brock allegedly ate. Chilling doesn't begin to describe it.