The 62 imported sheep, upon arriving at the sound stage, immediately went to work on the bracken and bushes that had been brought with them. The infuriated crew had to replace the real plants with ones hastily bought from a local nursery.
Before filming the scene where Robert Donat and Madeleine Carroll run through the countryside, Alfred Hitchcock handcuffed them together and pretended for several hours to have lost the key in order to put them in the right frame of mind for such a situation.
According to one of his sons, John Buchan (upon whose 1915 novel the film was based) was impressed with the film, despite its departures from his original plot.