The movie shows Charles Whitman lacing up shiny polished combat boots. In reality, he was killed wearing white sneakers with black socks.
Police Officers Houston McCoy and Ray Martinez both shot Whitman during the final confrontation. The autopsy credited McCoy with firing the fatal shot, but he was not included in the movie.
Whitman actually killed the receptionist in the tower that day and did not let her go by forcing her into the elevator. He also killed two women sisters and one of the sons. They and another son were the only ones in the tour group. The other people the movie shows were not there, the other son survived.
The trunk that Kurt Russell carried had Cpl USMC when in fact Whitman had been busted to Pvt. Due to misconduct in the USMC.
In the movie, Charles Whitman is seen driving a dark-green Dodge pickup truck. In actuality, Whitman drove a black Chevrolet Impala on the day of the mass shooting.
Most of the police vehicles seen are mid-1970s Ford Torino sedans - Austin Police Department vehicles of the late 1960s would be a full-sized Dodge or Plymouth.
In this set-in-1966 docudrama, various police cars are seen sporting TwinSonic light bars. Such light bars were not introduced by Federal Signal until 1968.
The movie is set in 1966, but features clothes and cars from the 1970s.
Both ambulances seen throughout the film taking wounded victims to the hospital are 1973 Chevrolet models, seven years out of date for the movie's 1966 setting.
One of the cars used is a 1967 Chevrolet Caprice. On August 1st, 1966, this car would not be available to the general public until a month later.
The movie was filmed in downtown Baton Rouge, Louisiana, using the state capitol building as a stand-in for the tower on the University of Texas, in Austin. The Mississippi River is clearly seen in several shots from the top of the tower. There is no body of water that large close to Austin, where the tower is located.