Factual error: When Harvey sets up his very obvious "SOAP box" and gives his first speech, modern vehicles can be seen parked along the curb behind him, most obviously the small US Postal van and UPS truck. A little later, a 2000s era black SUV is at the curb when Harvey steps out of his camera shop.
Factual error: The character is given an effeminate voice. Harvey's voice was not at all effete.
Factual error: Dan White did not attend Harvey Milk's birthday party at City Hall as in the movie. It never took place.