Great episode. I was wondering how the hell they would pull off the train heist, but the solution was actually pretty simple and ingenious. Although it does seem a bit far-fetched that the engineers wouldn't still have SOME way to contact someone anytime they have to stop the train. Or that the wouldn't see or hear anything going on in the back.
But oh well. The whole sequence was still intense as hell.
And wow, Walt is really pushing his luck with Hank. Not only by planting a couple of bugs (which you would think a suspicious cop like Hank would be on the lookout for), but talking about how much Skyler "hates" him and considers him a "bad influence" on the kids.
That, combined with Skyler's depressed and traumatized behavior around Walt, should be setting off alarm bells
in Hank's head by now. Because her behavior isn't consistent at all with the story he's being told.
Not to mention the new cars and expensive watch Walt is buying himself...