The music that plays during the end credits is a rearranged version of the Breaking Bad (2008) theme.
Vince Gilligan said his enjoyment of creating the show has opened his mind to other spinoffs or shows set before or after Breaking Bad.
Bob Odenkirk initially turned down reprising his role as Saul Goodman as he felt Breaking Bad was fulfilling enough and he wanted to spend time with his kids. His kids assured him they'll be ok and encouraged him to come back.
Vince Gilligan said that the show would not go past six seasons, as the timeline would eventually run into the Breaking Bad timeline. "We have certain characters that need to be introduced and specific events that need to happen, but the writers have freedom to develop how we get there in allotted time available," said Gilligan in an interview.
Jeremy Shamos and Julie Ann Emery, who play the Kettlemans, were given freedom to improvise because the producers liked their dynamic so much.