Stone and Keller are faced with a possible "political assassination" when they are called to city hall to investigate. They are seen gathering information in the actual mayor's office at city hall. The mayor's aide (the fictitious Mr. Skowlownowski) tells Stone: "I have had it with these political assassinations... if you don't like someone else's views, you get a gun and blow them apart". These are ironic words, because just 6 years later, in these actual same offices, the real mayor of San Francisco, George Moscone and Supervisor Harvey Milk, were killed by former Supervisor Dan White who shot each of them multiple times, in one of the most infamous political assassinations in American history.
The newspaper that "Wally" the vendor holds up reads "Catholics Fleeing Ulster", which was a headline in January, 1972, indicating the time of filming.
As the popularity of the show grew, being filmed actually on the streets of San Francisco, crowds would gather at various filming locations throughout the city. At 15:09 as David Wayne's character goes into the bank to withdraw his money (followed by the bad guy -Robert Foxworth's character) you can see reflected in the windows of the bank a large crowd has gathered directly across the street to watch the scene. As the camera angle changes to film from inside the bank looking out at the exact same location -the crowd has suddenly disappeared.
At 49:21 (the epilogue for this episode) Wally is running around on his corner selling newspapers. The problem is - he is selling newspapers with the exact same headline he was selling in the first scene (opening of act 1)! The headline reads: Catholics Flee Ulster (revealing what was happening in Ireland in 1972).