Oh that one! That's just the shotgun leaning against the wall. Originally this was going to be a stealth game, and that opening door interaction is a left over from that version of the game. Picking up the shotgun was also the final objective of that version, so you can pick it up, but doing it in the menu for this version doesn't do anything (I actually forgot you could pick it up until I went back into the game and clicked on it in the menu lol) But yeah, just thought it would be fun to leave those things in the menu to poke at.