While Cohle reviews the paperwork about Reggie Ledoux in the car, the camera pans down through the details of several charges. Where the info is labeling the county where the crimes occurred, known as a "parish" in Louisiana, they misspelled the county/ parish name Vermilion with an extra "L" as "Vermillion".
When Hart and Colhe are interviewing Lange, towards the end of the scene, Lange is sitting and he straightens up the top of his head disappears. It is an obvious CG shot and he put his head out of the frame.
When the detectives review Ledoux's paperwork in their car, his SSN has an extra digit.
The exotic dancer Martin Hart pursues to the rave is driving a B4-series Subaru Outback station wagon. That body style wasn't available in the United States until 1999 (model year 2000), though the crime Hart and his partner are investigating supposedly took place in 1995.
Detective Rust Cohle uses Great Value brand flour to replace cocaine he steals from the evidence locker. This action takes place in 1995, but the logo on the bag was introduced after summer 2009.
When Cohle enters the members area of the The Iron Crusaders' biker club, the song "A History of Bad Men" by the Melvins is playing. The song is from their album A Senile Animal, first released in 2006.