A mysterious drug dealer named Heisenberg begins selling the purest meth ever cooked. You are Hank Schrader. You are the DEA agent in charge of catching the guy. Your brother-in-law is Walter White. He happens to be a brilliant chemist who works as a high school teacher despite being a genius and suffers from terminal lung cancer (and is very likely dying). On top of that, after spending well over a decade showing zero interest in Hank's line of work, he suddenly became very interested in how lucrative meth could be, and even asked to see an actual lab right after said diagnosis. Meanwhile, some chemistry equipment from aforementioned school is stolen and being used to cook meth. You'd Then Expect: Hank to connect the dots and realize Walt is probably the only person to fit Heisenberg's profile perfectly, or at least is involved in his gang in some way. Instead: Hank never suspects a thing... until Walt's own what an idiot moment. However, Hank also generally writes Walt off as book-smart but dumb at everything else, considering him to be a mild-mannered underachiever who "who wouldn't know a criminal if he was close enough to check you for a hernia," meaning his biases are obviously going to factor into the investigation. These biases might attribute to why Hank doesn't think Walt is Heisenberg until Season 5B.
In "Peekaboo", Walter wants Jesse to recover $1,000 of meth from a pair of addicts who stole it from one of Jesse's distributors, preferably without violence. You'd Expect: He'd tell Jesse this explicitly, or come up with a plan for getting it back. Instead: He tells Jesse to take care of business and to bring a gun.
About halfway through "Peekaboo", Jesse finds the addicts, pulls a gun on them and coerces them into handing over what they stole. You'd Then Expect: He'd keep them at a safe distance using the gun, or just shoot them on the spot so they couldn't identify him to the police Instead: He plays peekaboo with their son after they fall asleep.
In "Better Call Saul", Badger realizes he's probably getting set up as part of a drug sting when he notices what look like surveillance vehicles parked nearby, and the customer he's selling to is a little confident in himself. You'd Expect: He'd walk away and go back later for the drugs. Instead: Badger being Badger, the undercover cop manages to get him to fall for the old "undercover cops can't deny that they are cops when asked directly" urban legend. So Badger goes through with the deal, and is promptly arrested.
In "Sunset", Walt finds out that Hank knows about the RV and that he is surveilling Jesse's house. After consulting Saul he rushes to the yard where the RV is stored and orders its destruction. So far so good, but Badger is at the yard at the moment and asks Walt about Jesse. You'd Expect: Walt'd realize that Badger, being Jesse's buddy, would tell him about Walt's plan. Thus, you'd expect that Walt'd tell Badger that Hank is staking out Jesse's house and would follow Jesse straight to the RV. Instead: Walt ignores Badger's question.
In "One Minute," the Cousins ambush Hank in a parking lot. Hank disables Leonel, and then there's a brief exchange of gunfire between him and Marco, which ends with Marco shooting Hank twice in the chest, wounding him. Marco then steps up to Hank, pistol drawn: You'd Expect: Marco just put a bullet between Hank's eyes, since Hank is now incapacitated and clearly not in a position to fight back. Instead: Marco decides, "No, too easy," and walks back to his car to grab his axe. In the time it takes him to return with axe in hand, Hank manages to load the spare "Black Death" bullet that Marco dropped while reloading into Leonel's gun, and is able to shoot Marco in the head right when Marco prepares to swing the axe. To be fair to Marco, it's possible that he didn't notice that he'd dropped the "Black Death" bullet, but it still fits this....
In the Season 3 finale, Walt has Jesse kill Gale. You'd Expect: He'd destroy any evidence that he knew Gale. Instead: He keeps a book from Gale, with a note from the guy, in his bedroom where anyone could find it. Come season 5A, guess what happens.
In early season 4, Hank is at a dinner party with the Whites when he announces that "Heisenberg" has been found dead and was actually Gale Boetticher. You'd Expect: Walt would congratulate his brother-in-law for nailing a dangerous criminal, or at least keep quiet. Instead: He derides Gale as an amateur who couldn't possibly have been smart enough to be Heisenberg. Now, to be fair, Walt was inebriated, and Walt deriding Gale isn't out-of-character for him, as Walt's pride won't let anyone else get credit for what he sees as his, but still, saying it to Hank's face was enough to prompt Hank to reopen his investigation. Though later on, it's implied that, subconsciously, Walt is trying to get Hank to catch him out of the belief that he would be safe from Gus in prison and could drag Gus down with him.
Ted Beneke has been cooking his accounting firm's books with Skyler's help since Season 2, and the IRS begins to investigate him in late season 4 for embezzlement. You'd Expect: He and Skyler would meet together and work to get their stories straight, and maybe even hire a couple of good attorneys. Instead: He doesn't tell Skyler about the indictment until the day before his meeting with the IRS. And, to be fair, Skyler does seem kinda annoyed that Ted didn't notify her earlier about the audit, but it's still poor planning on Ted's behalf....
Skyler narrowly helps Ted avoid criminal charges by making it seem like the missing money is the result of ignorance, but he still owes the back taxes. Then he receives from Saul Goodman an inheritance check for the exact amount he owes from a relative he didn't know he had. Money that... You'd Now Expect: ...he use to pay the IRS because that was obviously the intent of whoever sent it. Instead: ...he uses to buy a Mercedes, figuring he'll eventually get a better offer. This forces Saul to send Huell and Kuby to force him to sign the check.
Mike (by his standards, at least) in early Season 5: all right, tying up someone to a radiator by one hand with temporary handcuffs is perfectly reasonable. You'd Expect: That as Mike is doing it to someone he just called out for being a loose cannon and who is a genius at escaping, either use a second set of handcuffs, or clear the immediate area of objects that could be used to break these handcuffs. Instead: He leaves Walt unattended long enough for Walt to undo his restraints.
In "Blood Money," Hank has figured out that Walt was Heisenberg and puts a tracking device on Walt's car. You'd Expect: That Hank would remember how he showed a tracking device to Walt when he asked him to put on Gus's car in season 4, and put on a tracker in a location that Walt won't think to look. Instead: Hank uses the exact same kind of tracking device that he had Walt put on Gus's car, which ensures that Walt knows exactly where to find it. Even Worse: It gets even more idiotic if you remember how in "Dead Freight," Hank chewed out another agent for planting tracking devices on the methylamine barrels at the Madrigal warehouse that weren't hidden well enough. To Hank's credit, though, it was several days before Walt found out about the tracker, meaning he can't remove it at own leisure like Gus did (Gus knew he was being bugged before the fact; by the time Walt found out about his tracker, he'd already visited Saul and Jesse); still, it was a bit of oversight on Hank's behalf where he was putting the tracker.
In the fourth to last episode, Hank finally has Walt right where he wants him: blinded by rage, irrational, and leading Hank right toward a mountain of irrefutable evidence of Walt's wrongdoing. You'd Expect: Hank to immediately call for backup and bring the full force of the DEA down on Walt, complete with choppers and squadrons of agents and cops in SWAT gear, or at the very least, phone his findings in to other men at his office so that if the worst should happen, his investigation won't die with him and someone else takes Walt down. Instead: He shows up with Gomez and a couple of guns and tells no one where they're going or why. Enter a bunch of heavily-armed neo-Nazis, and well, we all know it ends for them.
Speaking of that, in the antepenultimate episode, Jack Welker has killed Hank and Gomez, captured Jesse, and stolen every barrel but one of Walt's millions of dollars. You'd Expect: Having stolen his money and killed his brother-in-law, Jack just kill Walt, a man he knows must despise him. Instead: He lets Walt go, and we all know how that turns out. Additionally: It's a strange decision since Jack clearly has no loyalties to anyone but himself and his fellow Neo-Nazi crew, so it's all the stranger when he leaves alive a witness who now has a million reasons to want him dead. It's partially handwaved in that Jack says that Todd respects Walt and would be angry with Jack if he were killed. Some fans even argue that Jack left Walt alive to keep the heat on Walt (since killing him would just lead the police to look for Jack's crew), but still, it's enough to qualify for this page.
In the series finale, Walt confronts Jack and his white supremacist gang. Jack quickly decides to kill Walt, who then accuses him of having gone into partnership with Jesse. You'd Expect: Jack to just laugh at Walt, tell him that he's holding Jesse prisoner and then shoot him dead. Whether or not Walt knows the truth of the situation isn't going to matter a whole lot when he's dead, and everyone else there knows exactly what's going on. Instead: Jack acts all offended, and then has the chained-up Jesse dragged into the room just to let Walt know how wrong he is. Walt then actives a home-made automatic turret in his car's trunk, which kills the entire gang (and mortally wounds Walt), leaving Jesse as the only survivor.
In the first episode, Jimmy hires two skaters to jump in front of Betsy Kettleman's car as part of his scheme to get back into her good graces. He gives them information about the car and the route that Betsy takes. He even tells the skaters important information to memorize, like the license plate and the specific shade of brown on the car: You'd Expect: That the skaters would maybe write this down and maybe even take a picture of the car. Instead: They target a stationwagon that's a similar model and similar in color to the Kettlemans' car, which happens to be driven by Tuco's grandmother.
From the above, the car hits one brother and they start their act. But suddenly the car takes off. You'd Expect: The brothers to just call the police, since even though they were scamming the driver, the driver has committed hit-and-run. There are also lots of witnesses who saw the hit so can provide a license plate. Or alternately, that they wait for Jimmy to show up. Instead: They follow the stationwagon to another house and end up in Tuco's captivity.
Add to that, when the stationwagon arrives at the house, the driver, an elderly Hispanic woman, climbs out: You'd Expect: That the brothers would immediately realize that there's no way this non-English speaking granny could be "Betsy Kettleman" and just go on their way. Instead: They follow her into the house and continue to try to get money from her, with one of them calling her a "bizznatch". For this, Tuco beats them up andcomes close to using brutal methods of murder/torture on them and Jimmy has to talk Tuco into breaking only one leg on each brother.