Black Mirror 1 consists entirely of pre-rendered content. The "3D" characters you see in the game are all bitmap graphics, drawn as sprites. The dev's next game Ni.Bi.Ru. added realtime 3D characters, but Black Mirror didn't have that. Since everything is pre-rendered for a fixed resolution and there is no 3D geometry, anti-aliasing won't work in this game. Same for texture filtering: The only thing that might use and benefit from texture filtering would be scaling the pre-rendered character sprites. I think the player character is the only sprite that might have any scaling applied to it. The other characters just walk a predefined path or stay at a fixed position, so they probably just use the pre-rendered sprite bitmaps without any scaling applied to them.
I once wrote a tool to export all of the games graphics, that's how I learned that it's all just bitmaps (as in .BMP files). I never published my tool, but if you look online, you might find other tools that let you extract the data.