Factual error: When Janet Leigh is shown lying dead on the floor of the shower, there is a close-up of her open eye. The pupil is contracted to a pinpoint (obviously due to the bright lighting) where it should have been dilated. After the film was released, Hitchcock heard from several ophthalmologists who pointed this out and suggested he use belladonna eye drops in the eyes of "dead" people in future films, as the chemical prevents the pupils from contracting. (00:48:30)
Factual error: When the two scholars are in the carriage, they mention being 6-7 versts from Mirgorod, and that means that they will be probably late for the inauguration but still able to make it to the conference "in the evening", in Moscow. That is, if they don't waste time dining at the inn. A little rest seems the last of their problems: while Mirgorod (Myrhorod) is certainly closer to Moscow than Moldova, mentioned before, it's still nearly 900 kms, over 850 'versts' if you will! That's a trip they would make in a week, being optimistic, surely not in a day or overnight.