Death Is the Only Answer (TV story)

Plot
When the Doctor is reunited with his Fez, he trips over onto the console, knocking off his the fez and hitting a lever. The Fez vanishes and Albert Einstein appears from nowhere, with the Fez on his head. He had been working on his time machine, and thought he'd found the vital part of it - a mysterious liquid which Einstein believed to be bionic fusion liquid. But Einstein got it wrong. When he walks away from the console, the liquid spits up at his face despite the Doctor's warnings, turning Einstein into an Ood. The Doctor manages to turn Albert back into his normal self, and stops him from feeling sick with help from the Sonic. The Doctor drops Albert off in 1945, and leaves for another adventure with a bit of goo left on the floor.

Cast

 * The Doctor - Matt Smith
 * Albert Einstein - Nickolas Grace
 * Ood - Paul Kasey

Continuity

 * Albert Einstein gets temporarily turned into an Ood. Their last appearance was in DW: The Doctor's Wife.
 * The Doctor mentions that Einstein's toothbrush was destroyed by the Daleks during a recent (unspecified) encounter.
 * The Doctor states that "This old Trash will be around until the end of time. In fact, it was."
 * This is the second time Einstein has been in the TARDIS, the first time was with The Seventh Doctor in DW: Time and the Rani explaining that the TARDIS was all relative. He once had his picture taken with the Eleventh Doctor and Father Christmas at Frank Sinatra's hunting lodge.
 * The Doctor has obtained a new fez (apparently originally owned by Einstein) and he mentioned River Song blowing up the last one (DW: The Big Bang).

Timeline

 * This story occurs after: DW: The God Complex
 * This story occurs before: DW: Closing Time
 * This story occurs during the period that the Doctor was having a "fairwell tour" of adventures, as seen in DW: The Impossible Astronaut

Behind the Scenes

 * This special was broadcast on BBC Three as part of the Doctor Who Confidential episode When Time Froze.
 * Aspects of this episode's production were covered in a regular "Script to Screen" feature, which appeared in every Confidential episode from River Runs Wild through its premiere within When Time Froze.
 * A shortened version of the Doctor Who opening titles was used.
 * This special's only on-screen credit was that of the authors, the Children of Oakley Junior School.
 * After being cast as the Eleventh Doctor, Matt Smith famously wrote several (unpublished) Doctor Who short stories, in order to help him prepare for the role. According to several interviews, one of these stories featured the Doctor meeting Einstein.