Word of God:
- Vince Gilligan provided an explanation (during Comic Con 2013) as to what took place when Walter had Brock poisoned off screen.
Vince Gilligan: That’s an excellent question and my writers and I would always tell the stories to ourselves of the evil juice box man
who somehow… Our best guess is… I can tell you that the way we worked it out in our timeline he had just enough time to do it but it would have been very tricky indeed and it was improbable perhaps but not impossible. That he could have got in over once he got that idea you know spinning the pistol by the pool and waiting to die essentially, looking at that lily of the valley, contemplating the idea at that point… Uh I think at that point what he did is he kind of crushed some of the stuff up, put it in a juice box or something and then somehow snuck into, being a guy who’s a teacher, he knows his way around a school, probably got into Brock’s nursery school and swapped it out. This is kind of the inner story for how it happened for the writers and I, but it would have been tricky timing. He was a very motivated individual at that point; he had to save his family, that’s my best guess on how it actually happened.
- Gilligan has also revealed what happened to Jesse after he was saved from being a slave to the Nazis. He managed to get clean and start a wood shop, living happily ever after. Since Vince Gilligan is a major believer of karma, he seems to think that Jesse needed this after all he went through over the course of two years.
- Walt saving Jesse in "Felina." Its confirmed that Walt was planning to kill Jesse but he couldn't bring himself to do it.