Near the end when Jimmie visits Mont on the boat dock, the tide is clearly out. Seconds later when they hug there is water all around the dock.
(at around 1h 12 mins) When the two rival men confront each other regarding the shooting murder of their mutual friend, one man is holding flowers; then they disappear from his hands as he hugs the other man.
At around 29 minutes, Jimmy is seen telling tourists about the history of the house. At first, his mouth is covered in blood from falling. After it cuts back to the tourists and back to him, there's no blood.
When Jimmie and Mont first visit the house, Jimmie says that the railings are Periwinkle, not black. Periwinkle is a light blue/violet, not anything close to black.
It is repeatedly said the house's location is at Golden Gate and Fillmore. When the house is first seen, however, the camera pans away, and a somewhat blurred street sign can be seen that says "20th". Neither 20th St. nor 20th Ave. is anywhere near that location. Articles about the making of the film note that the house that provided exterior location shots is actually on So. Van Ness between 20th and 21st Streets.
You can clearly see Pot Hill in the background, which makes this Folsom St and not in the Mo on Golden Gate.