Fascinating interview with Moira Walley-Beckett and Rian Johnson, the writer and director (respectively) of last night's awesome Breaking Bad. Spoilers if you haven't seen the episode. They go really in-depth into the episode, and there's some interesting revelations:
The opening flashback scene was the very last scene shot on the series. They waited til the very end to shoot it because they needed to shave Cranston's beard off for it.
As mentioned in the post title, the baby's lines weren't scripted. She just suddenly spoke during the scene (her mother was right off camera) and Cranston rolled with it.
There's plenty more, and well worth the time reading it.