Doctor Who fans in the US are being urged to keep the plot of Saturday’s finale secret after DVDs of the series were sent out early in error.
It appears “a small number” of fans had been sent pre-ordered DVDs three weeks early.
The show’s producers asked those with the DVD not to reveal plot details which would ruin the “viewing pleasure” of others.
They promised footage of current Doctor Matt Smith with predecessor David Tennant “if everyone keeps the secret”.
“A small number of US Doctor Who fans have received their series seven part two DVD three weeks early,” BBC Worldwide said in a statement.
“We are asking fans who may have the discs not to divulge plot details so that fellow fans who have yet to see the episodes do not have their viewing pleasure ruined.”
The statement said BBC Worldwide was “currently investigating how this has happened”.
Doctor Who fans in the US are being urged to keep the plot of Saturday’s finale secret after DVDs of the series were sent out early in error
It added executive producer and lead writer Steven Moffat had promised the special video featuring Matt Smith and David Tennant if the secret was kept.
Saturday’s episode of the BBC One show, The Name of the Doctor – written by Steven Moffat – comes ahead of a 50th anniversary 3D special, due to air on November 23.
David Tennant and Billie Piper, who played his on-screen companion Rose Tyler, are among those who will guest star.
David Tennant starred in Doctor Who from 2005 to 2010, while Billie Piper first appeared in 2005 opposite Christopher Eccleston, who played the ninth Doctor.
In May 2011, Steven Moffat criticized those “who call themselves fans” who revealed crucial plot lines ahead of transmission.
“You can imagine how much I hate them,” he told BBC Radio 5 live.
“I wish they could go and be fans of something else.”
He said it was “heartbreaking” when a fan, who had been invited to a press screening but asked not to give away spoilers, had posted the entire plot of two episodes on an internet forum “because you’re trying to tell stories and stories depend on surprise”.
“So to have some twit who came to a press launch, write up a story in the worst, most ham-fisted English you can imagine, and put it on the internet [is heartbreaking].”
The 50th anniversary of Doctor Who was marked at Sunday night’s TV BAFTAs with a video montage while Jenna-Louise Coleman, who plays current assistant Clara Oswald, presented an award.
Doctor Who’s 50th anniversary special will see the return of David Tennant and Billie Piper.
David Tennant was the 10th Doctor and Billie Piper played his on-screen companion Rose Tyler in the show.
Filming on the show, which will also star John Hurt, will start next week.
Doctor Who’s 50th anniversary special will see the return of David Tennant and Billie Piper
David Tennant’s successor, Matt Smith – also in the special with his new assistant played by Jenna-Louise Coleman – says fans “will not be disappointed” by the 3D show, due to air on November 23.
Billie Piper and David Tennant have long been rumored to be making a return for the special, which is being written by the show’s executive producer and lead writer Steven Moffat.
In January, Billie Piper, appearing on the Graham Norton show, denied she would be appearing.
“I wasn’t asked, no,” she said.
“I think Matt Smith may have said, in passing or in jest, it would be nice.
“I think maybe he said that and then it became something quite different, but no.”
Matt Smith has said the show “manages to pay homage to everything – and look forward”.
“I read it and I clapped at the end. I think it’s hilarious, it’s epic and it’s vast,” he said.
Steven Moffat, meanwhile, has said he took special care to protect the secrets of the story.
“One length I’ve gone to which is a really good security measure – I make sure I don’t get a script, because I will lose it,” he said.
“I forbid people to hand me one. It’s on my computer under lock and key.”
The first story of Doctor Who’s 2013 run, The Bells of Saint John – described by Steven Moffat as a “proper London thriller” – will be screened later.
Viewers will see the Doctor and new companion, Clara, played by Jenna-Louise Coleman, battling an evil entity in the world’s Wi-Fi networks.
Future episodes see the return of the Cybermen and old enemy the Ice Warriors, who last appeared during the Jon Pertwee era in 1974.
The first episode of Doctor Who, An Unearthly Child, starring William Hartnell as the Timelord, was broadcast on November 23, 1963.
As part of the anniversary events, the BBC will also broadcast An Adventure in Space and Time – a one-off drama looking at how the sci-fi show came to be made.
Doctor Who: The Bells of Saint John will air on BBC One at 18:15 GMT on Saturday, March 30.