Almost fully is a half-documentary improvisation.
The short scene after the end credits is the only one in the movie to have an audible line.
Titles and credits background is camouflage pattern known as "Dubok" and "Butan" (three-colored summer field uniform of A type), which was crafted in 1984 for Soviet army. After the fall of USSR it's normally used in Ukraine. It's actually the type of camouflage that can be seen worn on film's characters.
Mykola Yeriomin: [multilinguality] While the film is in Russian, there are a few signs/stands in Ukrainian seen.