Tinker, Tailor, Liar, Thief - S8-E15
Revealing mistake: In the second close up shot of Nigel Atkins lying dead, after Jessica drops her Harrod's bag in the chair, it is obvious he is still alive as you can see his pulse on the side of his neck.
Murder, She Wrote (1984)
1 mistake in Tinker, Tailor, Liar, Thief
Trivia: This is the only episode in the entire series where the victim is attacked but is later revealed to be still alive.
Question: Why did Lane Henderson (Louise's father) murder his wife?
Answer: In a flashback scene, it was shown that he had a violent temper, so it stands to reason that he finally killed her in a fit of rage.