The filming location for Harvey Milk's business, Castro Camera, was the real storefront where the actual business had once been. At the time of filming (mid-2008), it was a gift shop called "Given"; the film crew worked with the owner of the gift shop to recreate the look of Milk's camera store inside the space and restored it to its 2008 appearance after filming.
During a July 2008 interview with the Orange County Register about Pineapple Express, the interviewer told Seth Rogen and James Franco that he prepared for the interview by watching the classic stoner comedy Fast Times at Ridgemont High the night before. When he asked Rogen and Franco if they prepared likewise before making Pineapple Express, Franco said he prepared by making out with Spicoli (a reference to his having shot Milk, in which he and Sean Penn play lovers).
It was widely reported that while filming a scene at the old Castro Camera, some of the actors claimed that they saw a man come in and sit on a couch. After the scene was filmed, nobody else claimed to have seen the man, and the actors themselves went on to claim that it was perhaps the ghost of Harvey Milk.
Veteran police officer and actor Brian Danker, seen in this movie in his first speaking role in the homicide scene, actually served in Vietnam from 1970 to 1971 in the same unit as Dan White - the 173rd Airborne.
On Roger Ebert's year-end list of the 20 best movies of 2008. Ebert did not rank his picks this year, opting instead for an alphabetical list. (He later said that Milk was the most deserving of all the Best Picture Oscar nominees.)
The last public appearance of Harvey Milk's life, two days before he was killed, was attending a San Francisco Opera performance of Puccini's opera "Tosca" featuring the legendary Italian soprano Magda Olivero. Not only is this event depicted in the movie, but it was in honor of that appearance that the filmmakers chose to use "Tosca" for all the operatic music heard in the film.
During the sequence dealing with Proposition 6, one of Milk's friends says "Even Reagan doesn't support it." Former Governor Ronald Reagan was so opposed to the measure that he publicly went against the Republican Party on the issue, even though he had been mentioned as a serious candidate for the Presidential election in 1980 and risked alienating his conservative support base. His support was given a great deal of credit for Proposition 6's defeat and contributed to his growing national profile ahead of his two elections as President of the United States.
Dustin Lance Black:
The screenwriter appears as one half of the couple that walks by the Castro camera shop after it's closed, when Harvey Milk is inside and one of the men asks if Harvey was going to win this time.
The trivia items below may give away important plot points.
At the end of the film, images of the actors costumed as their characters are replaced by photographs of the real people the actors portrayed. Many of these photos were taken by Daniel Nicoletta, who is the photographer played by Lucas Grabeel in the movie.
The real Danny Nicoletta has a cameo in the film as the person in Harvey Milk's office before Milk gets assassinated by Dan White. In real life, Nicoletta was the last person to speak to Harvey Milk in his office at San Francisco City Hall, just before his assassination.