The street corner at which the TARDIS reappears after being sent back to 2006 is the same street corner where Rose's father was originally struck by a car and killed in the opening of Father's Day (2005) prior to Rose altering the circumstances of his death.
In an acting master class at the Theatre Royal Haymarket in July 2011, Christopher Eccleston expanded the reasons for his leaving the show. He cited creative differences with "the senior people" on the production and stated he did not like "the culture" of working on the production.
Initially, the Controller survived into this episode to provide the Doctor with someone to talk to, until Russell T. Davies decided it would be more effective to have him converse with the Emperor Dalek instead.
The Ninth Doctor looks at his right hand before he regenerates. His next incarnation does the exact same thing twice.
The Ninth Doctor's pre-regeneration statement, "I mean it's a bit dodgy this process, you never know what you're gonna end up with", echoes the Fifth Doctor's post-regeneration statement in Castrovalva: Part One (1982), "That's the trouble with regeneration, you never quite know what you're going to get".