Factual error: The nuclear physics in the reactor scenes is laughably incorrect.
Visible crew/equipment: After Rokon's message in episode four, Eldra starts ranting and raving. A BBC camera can be seen in the doorway behind the Doctor and Sarah.
Revealing mistake: At the climax, when the Doctor and Sarah are setting up the scarf trap, the Doctor bumps a rock, which wobbles.
The Doctor: This is a situation that requires tact and finesse. Fortunately, I am blessed with both.
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."