Factual error: In the final scene, where Fonda and Holbrook are looking over the carrier at the crowds on the dock, you can see that only the first rows of people are dressed in period clothes. The rest of the crowd are dressed as they would have been in 1976 when the film was made. Also, between them in the background is a yellow Ford Pinto.
Other mistake: The chronology of dates on the teletype printer at the end of the film are not in the correct order. We see "March 13, 1975" followed by "January 3, 1975", which is then followed by two August 1974 dates.