On the main show page, Doctor Who isn't displaying Next Episode: http://www.tvmaze.com/shows/210/doctor-who
However it is listed on the Episodes page: http://www.tvmaze.com/shows/210/doctor-who/episodes
Special Dec 25, 2016 The Return of Doctor Mysterio
I assume this is because it is a "Special".
That is correct, specials don't show up as the 'next episode' currently. Staff is aware of several issues with specials, this is one of them.
By the way, there was previously a full discussion thread about another Christmas Doctor Who special:
http://www.tvmaze.com/threads/865/doctor-who-christmas-special-not-displaying-as-next-episode
Additionally, if you're bugged by this and want to see it improved, head over to http://www.tvmaze.com/forums/6/pending-features and vote for "Better handling of specials" :)
Thanks david, I somehow missed that when browsing pending features, voted. It bugs me enough that I'm willing to help implement it. :)
Thanks gazza911, I didn't realise it was a controversial topic.
