When DC pulls out the pistol from its holder in the generator chamber, its sound is identical to Return to Castle Wolfenstein (2001) when the player swaps weapons. Similarly, when the soldiers emerge from the truck, the slamming noise is the same as in RTCW when the player attempts to open a locked wooden door.
While it wasn't specifically stated in what country the plot takes place (only mentioned that it's Eastern Europe), the sequel reveals that the bunker's located in southern part of Serbia, not far away from a town Backa Palanka, near the Serbian-Bosnian border, which is Central Europe, not Eastern.