When Mr. Rhinelander gets on the cable car, it is car 525. The car number then changes to 510 as it passes up Powell Street, and finally 309 in the shot where he gets off.
When the SFPD black and white unit leaves to back up Stone and Keller on the chase there is part of a jacket or other article of clothing hanging out of the lower corner of the passenger side door. When they arrive at the shootout it is no longer there.
When Stone walks up the stairs after one of the suspects falls after being shot, a cameraman in a blue shirt is clearly visible on the left side of the screen filming.