This movie was made under the working title, "Bats with Baby Faces", but Director Sir John Mills was persuaded to change it on the grounds that people might think it was a Hammer horror movie about vampires. Many critics noted that the new title, "Sky West and Crooked", would simply be incomprehensible to the casual movie-goer, although its meaning is explained in this movie. (The phrase "sky west and crooked" refers to someone who, as portrayed by Hayley Mills, is slightly mentally challenged).
Hayley Mills revealed in her memoir that she was struggling with bulimia during production of this film.
According to Hayley's book, Andrew, her boyfriend, was hired as an assistant. Andrew had a fascination with graveyards and took Hayley to the graveyard a couple of times, in the evening, to listen to music and look around. One night, Andrew found a skull and a few human bones. He took them to his hotel room. The next morning, he laid them out onto the bed for the maid to discover. Hayley said that the maid gave everyone a heart attack with her "bloodcurdling" scream.