Another thing to keep in mind is all of the recesses in the block above the flange for the oilpan at the base of the block.

If the oil filter was loose, a significant amount of oil can leak past the filter gasket and seep down the backside of the block, collecting at the base.

When I first changed the oil on my B18B, I spilled a significant amount of oil removing the old filter, so I know that a half-cup or so can pool up there without question h:

Another thing to check out is the solenoid valve for VTEC operation in the head. Check the camshaft seals as well. Although somewhat unlikely, it's a good thing to check too.