Present day Darby (Emma Corrin) dyes her hair to a more vivid pink before dinner and suddenly has one inch thick dark roots (not present before). After dinner, in the hot springs scene, her hair returns to a washed out pink on blonde with barely any dark roots present.
Darby's gloves when finding the remains in the basement. She's glimpsed removing one, but next view she has both on, only to have neither on moments later getting the ring from the envelope.
When Darby arrives in Iceland, the temperature is announced as -7 Celsius (19.4 F). Later, after sunset she goes for a walk outdoors. It should be even colder than it had been during the day, but her breath is not visible. She's not even wearing any kind of cold weather protection (jacket, hat, etc.).