2001 BMW 740 Smoking upon startup

I recently replaced my oil separator valve/rear intake cover and gasket, along with the throttle body gasket and intake manifold gaskets. Shortly after, I replaced the valve cover gaskets and upper timing cover gaskets.

Immediately after replacing the valve cover gaskets and timing cover gaskets, I noticed the car started smoking at startup. I just replaced the rear valve, so I know that's not the issue. Some people have told me the oil separator/cyclone (inside the timing cover) is bad.

My question is, what else could be causing this? Could I have knocked a chunk of gunk into a drain tube somewhere causing oil to back up into the intake? This problem wasn't happeneing until I replaced the gaskets, and I didn't even touch the cyclone (especially as it's tucked away behind the timing chain. I highly doubt that by some estonishing coincidence the cyclone failed at the exact time that I replaced these gaskets.

Thanks very much for any assistance!