Crime mapping today is not the same as in the movie, but more like a machine making sense of lots of crime data and then predicting what will happen next.
Around the same time, dissection and studying anatomy was huge, and the human body was starting to be thought of as a sentient machine made up of complementary parts.
A mill is a place where machines make products. It is like a factory. For example, a paper mill makes paper and a steel mill manufactures steel. A mill can produce just about anything.