There are just two things about the third series I just don't get, in the first episode (Smith & Jones) why does The Doctor suddenly end up in hospital & why, when there on the moon, does he change his suit.
Well he answered the first question in the episode itself, at least: he checked in as a patient because he knew there was some strange energy source in or around the hospital and so he pretended to be ill so that he could get in and investigate without arousing suspicion. (Posing as a cleaner might have been a better move, but not really his style.)
Quite a good answer joko, but if you watch at the end of the episode he's got his pin-striped suit back on. so why did change into the blue one & not the pin-striped one.