One scene of Knives Out is totally out of otherwise magnificent plot with concise logic. What happened in the laundry at 1209 Columbus Rd before 10AM?
As the movie says after using a huge overdose of morphine you have about 10 minutes before you die. That is absolute key premise for the whole plot. How could Ransom possibly inject morphine to Fran within 10 minutes before 10 am or any close to it? As he was with Marta discussing the report etc. including car chase, to finally be captured by the police. Or how could Fran in the laundry possibly be still alive when found at that time by Marta, long long time after huge overdose of morphine?
My take: The only way I see it is fatal error in the plot. Marta had to find Fran alive to make the final scene more dramatic, and to bluff Ransom to make him confess. So 10 minutes limit simply went out of the window, or should I say main premise of the plot went out of the window.