Howard paying Chuck out of his own pocket to fuck off... While I still sort of struggle to understand how he could be rich enough to do so, yet the firm would be bankrupted were it to follow the same course of action, the emotional impact on Chuck was gargantuan. As much as it might seem that it was Jimmy coming by the house that tipped Chuck back over the edge, I think the realization that things had gotten so out of whack that one of his closest, if not his closest, friends saw fit to pay for him to leave out of his own pocket was ultimately what sent Chuck off on his downward electrical spiral.
I freely admit to being one of the dislike-Chuck brigade, but there are, or probably were, tangible depths and complexities to his character that make standing in judgement of him a complicated prospect.
Howard handing him the personal check, then asking for "...just one more thing," leading the applause with a cheesy, forced grin on his face then stalking away before Chuck's ovation was finished, simply superb television, with nary a car chase or gun shot to be found.
Although, Nacho and Gus might well be able to provide those at a later date. So much quality acting without a word being spoken between those two. Only Mike glowering in the background was missing...