Copacetic was in popular use. It was interchangeable with Jake.
A flatfoot was a beat cop
A gumshoe was a private detective
Women were referred to as Dames, Dolls, Frails, Molls and Skirts.
A pistol was a Gat or a Heater
A Sap was any device such a a sock full of lead shot, used to knock someone senseless without breaking their skull.
However, anyone of particularly dull wit or easily bamboozled might also be referred to as a Sap.
An informant was a Stool Pigeon, a Stoolie, a Rat or a Fink.
To be in prison was to be in Stir. or In the Stripey Hole.
If you were new to the big city, from a backwater or the country, you were a Rube.
If you were a Hipster or Hep Cat, and you were ethnic, you were a Zoot.
My father, from a Portuguese part of the Bay Area, dressed like this in the late 30's