Although the previously released trailers are not for the "Doctor Who" 50th Anniversary Special, they are for the limited edition "Fourth Doctor Time Capsule" box set, which tells the tale of the Zygons who are set to return this November.

As reported by Digital Spy, only 5,000 units will be made of this special box set, which is centered on the four-part story "Terror  of the Zygons" by Robert Banks Stewart about the shape shifting monsters.

"The Zygons are in there with all the others, particularly the Daleks and the Cybermen," says Stewart regarding the 50th Anniversary episode.

"[But] nobody yet knows what the plot of the 50th will be. Steven Moffat and his team in Cardiff, they are quite rightly keeping it all secret."

Within the "Fourth Doctor Time Capsule," Doctor Who fans will find:

-A Four Doctor action figure

-Interview with actor Tom Baker who portrayed the four iteration of the Doctor

-A Fourth Doctor sonic screwdriver

-An audio version of the story "Genesis of the Daleks"

-The novel "Tomb of Valdemar" by Simon Messingham

-Art cards of all the Fourth Doctor's companions

-And a letter from Tom Baker himself.

So, despite not being directly related to Matt Smith or the current story leading up to the 50^th Anniversary Special, "Doctor Who" should try to get their hands on this limited edition collector's item when it releases July 29.