The series is not due to be screened until late next month on BBC1.
But a black and white version without special effects has found its way on to the internet.
BBC bosses are already investigating how a number of scripts for the show had escaped their clutches ahead of the latest run with Capaldi as The Doctor, replacing Matt Smith.
The corporation's commercial arm BBC Worldwide reminded fans that it is illegal to obtain and share the footage.
It said of the latest leak: "This is part of BBC Worldwide's ongoing security investigation into leaked unfinished Doctor Who materials.
"This content is currently being removed and originates from the same Miami server we disabled last week.
"We'd like to thank the amazing Doctor Who fans who are continuing to keep fansites and social media spoiler-free but would remind those downloading and sharing this material that it's illegal to do so."
The new series begins on August 23 but stars and producers are taking the show on a world tour prior to the launch, kicking off in Cardiff, where the programme is made.