I read somewhere that since the appearance of John Hurt's character, all the regeneration cycles have now been used up - remember, David Tennant's Doctor had another regeneration after he was exterminated in the final episode with Catherine Tate.
So how is Peter Capaldi's Doctor making it in? Have the regeneration cycles limit been scrapped?
Also John Hurt's character was seen regenerating in the 50th anniversary... but weren't all the regenerations used up?
Or maybe something happens around the parallel world Doctor and Rose... maybe the Doctor comes back with just 1 heart? Part timelord, part human?
Or is there something going on with the Doctor's daughter? - In the David Tennant era episode, they thought she had died at the end yet she appeared to regenerate and come back to life.
All very confusing and a lot of strands here that need to have an ending!