Homelessness was most certainly part of that time. More so, because at the beginning of the 20th century there was still not much of a social safety net.
Also, at the end of the movie it says: "4 days later San Francisco was hit by the great earthquake and fire of 1906.
3,000 killed, 250,000 homeless, and most of the ciy destroyed"
My observation was the incredibly broad road as well as the lack of rules in traffic (suddenly changing lanes etc). A lack of traffic signs, and a lack of physical commercials. It was snowy (which might've meant everyone drove slower), and people were just walking in front of the traffic all the time, only moving out of the way at the last moment. Not only with cars, also with horses and trams. People (I mostly saw men and some children at the end, women not so much) were looking like gentlemen.
Children acting up before the camera was fun to see because its apparently from all times.
I also found the atmosphere rather serene, not like a city of nowadays. The lack of noise and lack of commercials help with that.
"The cars have license plates -- 4 digit ones, even. So the number of cars in the US, at least, was probably far less than 10,000."
Back then people didn't travel as much. The world was far less globalized, travel was expensive, and people stayed within the city or region they were born (ie. an example of less globalization).
So I'm not sure about this. I'm not even sure all the police departments were connected to each other. If a car is seen in San Francisco that license plate might also be in use elsewhere. Its something we'd need to look into instead of feel conclusive about. Thanks for sharing your observations though.