Genesis of the Daleks - S12-E4
Deliberate mistake: Chief of Security Nyder wears an iron cross on his uniform which mysteriously disappears in episode 3 - apparently the producers felt it was too close a reference to Nazism so it was removed from the show. (Source: DVD commentary).
Deliberate mistake: In episode three, the Doctor and Vira meet a half-changed Noah. He holds a gun on them, then drops it at Vira's feet and the door is suddenly closed. This is because the scene was originally longer and involved Noah begging Vira to kill him before the Doctor shuts the door. It was trimmed down to get it past BBC censors.
Deliberate mistake: Benton is a Warrant Officer in this story, but the end credits refer to him as "Sergeant Benton".
Chosen answer: No, it was the result of the Cybermen's draining Earth of energy to their world, that also affected the Doctor, draining his energy as well, causing him to regenerate.
Also In the episode it's said that his body was wearing thin.
Dan23