Yeah, exactly what Boggs, Rains and Golic are doing on their little foray in the film is left frustratingly vague. Some of their comments make it sound like they're mapping out an abandoned part of the facility, but why would anyone care about that? The book instead says they're foraging for abandoned supplies (kinda hinted at in the AC when Golic finds the cigarette machine), which at least makes a lot more sense but was seemingly changed for the film.
