Continuity mistake: One of the last scenes of the movie, when Karen Silkwood is driving away from Dru they show her sitting in the car waving at him and the rearview mirror is clearly visible. Then she starts driving away, and the rearview mirror is gone. Then as she drives off, you can see the mirror has been replaced.
Factual error: In the shot of the start of the race at Agua Caliente - some of the horses in the line up are wearing ring head bridles (an Australian stock horse type bridle) - it would be unlikely that these American horses would be racing in such bridles.
Continuity mistake: At the NAACP headquarters, Medgar Evers joins other people sitting at the table to talk with Sampson. The person sitting next to him casts a long diagonal shadow across the table in each wide shot, and a short one when the camera is on Sampson.