So I suspect this may be a engine or programing issue but this game has a medium to severe problem with reloading a level within a loaded/restarted session.

Aside from the glaring obvious loading issues of objects and even wall textures, map specific events seem to be bugging out, I'm currently in the VIP lounge level and sections of the map is acting as if it's flooded where I can swim in the air along with the audio effects to match.

Lastly and I don't expect this can be adressed unless there's a no-clip pickup at the end of the level but unless you get all the secrets and posters in one playthrough of the level, you're going to have to reset from the very start to get the secrets that you missed because sections of the map will be blocked off, this isn't a critique of a modern gamer, classic FPS's allowed you to get to the exit and have full access to the map to scour it for loose pick-ups and secrets (Painkiller, DN3D, Shadow Warrior, etc).

Right, I've given my 2 cents but I think the next patch should really address the level loading system, it's perhaps the biggest blemish this game has.