I figure I'd report it, since maybe some mod has actually fixed it. I long noticed that loading screens used an actual render, rather than just a picture. But this is confirmed for me when the crossbow show up, and it actually goes through the shooting animation. Maybe that isn't a bug?

It doesn't cause any problems, but it seems strange that just the one loading screen would be animated and the others are not.

The Crossbow was the most recent weapon addition to the game (as a type) so it stands to reason that it could act different than all the other screens they made for the base game.

And, your correct, the items shown on the loading screen are hi resolution ultra detailed renderings of items that are used in the game. You can even find them in the game content, just not in the game world.