Steven and Lapis both blow a raspberry at a rude driver in Jersey. This is a callback to Lapis' first appearance in the season one episode "Mirror Gem" when Steven first taught her this particular "joke."
Empire City is an amalgam of New York and Las Vegas (though, geographically, it's in the same part of the country as New York). Their motto, which Steven tells Lapis, is "What happens in Empire City never sleeps," which is a combination of the real life slogans associated with Vegas ("What happens in Vegas stays in Vegas") and New York ("The City That Never Sleeps").