The only two major weak points I can think of in BB are the S2 plane crash and Tuco's cousins. Mainly because both were given a lot of build up and were ultimately anticlimactic. Otherwise, nitpicking about specific lines or "slapstick" moments seems silly. Breaking Bad is unapologetic about its absurdity; it has always had a layer of dark humor from the very first episode and the very premise is arguably unrealistic. To me, stuff like that just doesn't detract from the show, because the dialogue, characterization, atmosphere, and storytelling is strong across the board.