I think I found a flaw.

Rating: 7/10 (3 January 2020)

I enjoyed the movie but was confused at the end. The vial labels are switched by Ransom. Somehow Marta realizes she's given the "wrong med" to Mr. Thrombey. Does she know this because she somehow knows about the label switch? No. She simply didn't look at the vial carefully? No. Nurses always look carefully. And even if she made a once in a lifetime wrong med injection it wouldn't be on the exact same night that Ransom had made his label switch caper. Detective Blanc says she knew because she could tell the slight difference in the viscosity of the liquids to be injected (there were two). That can't be because it turns out she actually did give the harmless med after all and not the morphine. If she knew the labels were wrong due to the viscosity then she would have given the proper dose of morphine regardless of what the label said and therefor not gone into a panic. So what made her think she'd given an overdose of morphine? Am I the only one stuck here? Did I yawn and miss a crucial line?