Series producer Marcus Wilson tweeted earlier today:
Thank you to an amazing dedicated and talented cast and crew. That's a wrap on the anniversary - it will be special!The special has been filming since 2 April - a longer shoot time than the 60 minute Christmas Specials. While it should be taken into account that the special has been shooting in 3D (which increases shoot times), it's a good indicator that the special is more than 60 minutes - but the running time is still to be confirmed.
— Marcus Wilson (@themarcuswilson) May 6, 2013
The 50th Anniversary Special will air on November 23.
[Source: Doctor Who TV]