Continuity mistake: When Dr. King approaches Poirot with the scopolamine syrup, in close-up Ustinov's hand is a bit lower on the glass, and, the woman in the background, who had her hand up, has it down; not that she has a choice, since you can tell she is forced to keep firmly her hand down her side to hold in place her skirt (the wind would otherwise make it flap around all over the place). (00:17:55)
Other mistake: At the beginning of the movie, Ginevra is reading the magazine but is interrupted by the outbreak of a thunderstorm. There is no rain at all, though, just the sound effect of thunder, with the car already wet at the beginning of the take to try to establish the illusion. (00:00:40)
