This ep is chock full of anachronisms. The 20th century guitar, the modern attitude and ambience of the club (or restaurant) crowd, the beautiful lady singer's hairdo and songs, the dueling pants worn by the frenchman, the modern attitude and office of the club manager and so on.
There was a 1984 film called 'Streets of Fire' where it looked like the 1950s but it was actually the 21st century and America had simply regressed to a 1950s look more or less. Or the 1958 film 'Teenage Caveman' where we think It is like 20,000 years ago but It is really a century or so from now after nuclear war turned
back the clock to the stone age.
It would have almost been possible after seeing this to think Maverick was really set in the 21st century after an economic apocalypse and oil shortage had turned the clock to the late 19th century. In fact maybe that is exactly what has happened. And eps that seemed to be set firmly in the 19th century by dates given are just Maverick's narrative inventions and he and his brother both live in the future. Or that Brett and Bart live in contemporary times and when they narrate their stories this is all what they think the 19th century looked like.