Movie Goof (anachronisms): In a scene where Harper Lee and Capote are eating in Kansas, there is a menu with prices in the background. It includes a hamburger for $ 2.25. That is well above, more than double, the price of a hamburger meal in Kansas at the end of the fifties.
Movie Goof (anachronisms): Perry's letter to Capote acknowledging receipt of the pornography closes with Perry's signature and address, which includes the ZIP code for the penitentiary. The ZIP code was not officially introduced until July 1963 and not widely used until some time after that date.
Movie Goof (anachronisms): During 1959 visit to small Kansas, writer Harper Lee (who is not an aviator) suggests that Capote stay "under the radar" - a phrase not in popular usage until three or four decades later.
Movie Goof (anachronisms): Early in the movie Harper Lee and Capote order drinks in a Holcomb, Kansas restaurant. At the time of the movie's action, Kansas was dry as a bone. You couldn't buy a drink in a Kansas restaurant until state liquor laws began to change in the mid '80s.
Movie Goof (factual errors): The two guards at the execution are wearing hats that display the insignia not of corrections officials, but of U.S. Army officers.
Movie Goof (anachronisms): Razor ribbon shown on the prison walls and fences was not invented until the late 1960s.
Movie Goof (factual errors): In Chapter One TC says no passenger trains stop at Holcomb - only an occasional freight. Yet Truman and Harper Lee arrive at (and she departs from) Holcomb by train.
Movie Goof (anachronisms): Vacuum-formed yellow "Dollar General" sign visible as Perry and Dicky are being brought in by the police. The Dollar General name was not used until 1968.
Movie Goof (factual errors): Perry is depicted as being substantially taller than Truman when in reality they were roughly the same height. This may have been done purposely to give Perry a more intimidating presence next to the frailness of Capote.
Movie Goof (anachronisms): There is a three-pronged electrical outlet in Perry's cell.
Movie Goof (continuity error): When both prisoners are brought in to be hanged, it is raining hard. Even though the distance traveled in the rain is short, there are no visible signs of the rain on their clothes or face.