In the sheriff's office, there are some shots of the bulletin board in the background. On the board is the FBI's Wanted Poster for Frank Morris, following his escape from USP Alcatraz. The Alcatraz escape took place in June of 1962, sixteen years after the events in the film.
Several times in the movie when we see a close-up of the cops driving in their car, you can see rows of houses behind them out the back window of their car, but in the immediate next wide angle shot they're out in the wooded countryside, with no houses anywhere in sight
At the beginning of the movie a graphic is put onto the screen to draw attention to the fictional date of the first attack. The graphic reads, "SUNDAY, MARCH 3". Later, as a lead-in to the second crime, the graphic, "SATURDAY, MARCH 24" appears on the screen. The narrator's voice adds, "Now, it is a rainy Saturday night, March 24, 1946, 21 days after the attack on lover's lane." 21 days from March 3 would indeed be March 24, but it also would be, and was, a Sunday, just as March 3 was. The second graphic and the narrator's script were incorrect.