Plot hole: In the scene where Mrs. Parker has comes to the Goodfellow house to complain about the flower arranging committee, she says she has a bad heart. When Grace comes down the stairs she only catches the end of the conversation where Mrs. Parker is saying, "Your husband must be told," and then she runs to the kitchen and gets a frying pan to hit Mrs. Parker over the head. Afer Mrs. Parker drops dead, Grace says, "Well, she said she had a dicky heart." But this was said when she was upstairs and she would therefore not have heard Mrs. Parker saying it.
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Keeping Mum mistakes
Visible crew/equipment: When everyone is taking the trunk upstairs, the shadow of a boom mic is visible above Maggie Smith's head moving around.