When Raul Vega is shooting at police, he fires 7 shots from a 6 shot revolver.
At the beginning sequence, young Tiago is listening to a record player to La Llorona, a popular Mexican folk song, and even says it is his favorite. Since the episode is set in the late 1920's and 1930's, and although the song was composed in 1850, the particular version that Tiago is listening to is the one sung by Chavela Vargas (the trademark tone of Vargas' voice is very clear), created in 1961.
The design of the tequila bottle Maria takes a swig from when visiting his son at his apartment is a Jose Cuervo's Tequila. While the brand did export its products to the United States since the XIX century, that particular version, with its characteristic shape of the bottle, did not exist until 1992.