Visible crew/equipment: In episode three, when the Doctor enters the Pavilion of the Summer Winds and shuts the door, the door slowly swings open again. A hand then appears from behind the set wall and pulls the door closed.
Revealing mistake: Zadek claims the water door into Castle Gracht is a foot thick. But it is obvious when the Doctor crawls through that it is paper thin.
Revealing mistake: When K-9 is cutting through the wall of the hut, the cut overtakes his laser at one point.
Castrovalva - S19-E1
The Doctor: That's the trouble with regeneration, you never quite know what you're going to get. (00:12:15)
Planet of the Spiders - S11-E5
Trivia: The first thing the Third Doctor does on-screen is collapse out of the TARDIS, which is also the last thing he does in that incarnation.
Question: I wanted to know what was the name of the episode where these cancerous creatures suck the bones out of you and turn you into a pile of mush - it was one of the first episodes I think.
Answer: I don't think this was a Doctor Who story. It sounds more like the 1966 film "Island of Terror" (although it did star Peter Cushing who played Dr Who in two Dalek movies around the same time).
Answer: Your right it is, "Island of Terror."