Other mistake: When poison is first put in the pot of tea, the first shot of breakfast shows Woodcocks sister stirring her tea which presumably is from the same pot, but she showed no sign of poisoning.
Johanna: Where have you gone, Reynolds. There's nothing I can say to get your attention aimed back at me, is there?
Reynolds Woodcock: I cannot begin my day with a confrontation, please. I'm delivering the dress today, and I can't take up space with confrontation. I simply don't have time for confrontations.