Towards the end of the movie when Robert Graysmith (Jake Gyllenhaal) goes into the hardware store where Arthur Leigh Allen is now working, the subtitle reads December 1983. When Graysmith is asked by Allen if he can help with anything, there is a calendar behind him that reads February 1980. In the next scene it says that it is now 7 1/2 years later in August 1991. This is a case of poor placement of props. It occurs in the movie at hour 2:30:31.