Continuity mistake: When the mayor of San Francisco signs the new 'gay rights bill,' he puts the pen to paper with his left hand in the far away shot. When the camera cuts to the close up of him signing the bill, he's writing with his right hand.
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.