Matt Smith told DS that fans should expect an "epic", "ambitious" and "badass" episode of the sci-fi drama that celebrates both the show's past and its future.
Jenna-Louise Coleman - new companion Clara - and Steven Moffat - head writer and exec producer - also spoke about why the 50th special is "not a full stop" but "chapter one of a new story".
"I think we've got a story about the Doctor - and what it takes to be the Doctor," said Moffat.
The anniversary episode - to be shot in 3D - will begin filming in the coming weeks under director Nick Hurran.
Doctor Who returns to BBC One this Saturday (March 30) with new episode 'The Bells of Saint John'.
> Doctor Who Matt Smith: 'Anniversary episode is one of the best ever'
> Doctor Who 50th special is "epic, hilarious", says Matt Smith
Doctor Who - new episodes in pictures: