Recently in Historical Fact Category

As your following the brief opening sequence set in 1971, the film flashes back to the scene that occured (according to the superimosed title) "Four Years Earlier" -Truman Capote's famous black and white ball. Now in reality that party was held in 1966 which is five years earlier.

Leopold follows Stuart back from 1876 to the present day. The next day Leopold wakes up at Stuarts apartment and is all confused and upset. Leopold yells at Stuart saying that Stuart could be Jack the Ripper for all he knows. Now Jack the Ripper didn't start comitting all of his murders till 1888. Leopold is from 1876. How does he know about Jack the Ripper, which is 12 years into his future?