In retrospect massive spoiler
Farrell's Russian landlord is always so happy to see him and inquisitive what he's up to; then, when Farrell's about to drive off for the weekend with Susan, the landlord leans out the window, "off for a romantic weekend perhaps?",
it's a signal that Farrell/Yuri's mission to have an affair with Brice's mistress is going as planned, especially with Farrell's reply, "It's not just a job, it's an adventure" (ostensibly referencing the Navy's slogan, but actually referring to his mission for the Soviets.