As revealed on the DVD commentary, Walt's temporary apartment home is actually creator Vince Gilligan's own condo.
When Hank is in the car after the phone call says he will be killed in one minute, a whole minute actually passes in real time before the cousins appear. The director made sure of that.
When Hank is sitting in his car towards the end of the episode, the time reads 3:07. This episode, One Minute (2010), is the 7th episode of the 3rd season (i.e., 3:07).
During the flashback at the beginning of this episode, Don Salamanca is seen sitting in a chair reminiscent of a wheelchair, like the one he ends up confined to later in life.
In the call with Gus, Walter is asking to let him have Jesse as his partner wearing and surrounded by pale green, visually illustrating the old Walt still exists. Later Jesse is wearing all blue with blue sheets.