Point it out to the GC...nails shot that didn't make it in the joist are no big deal, providing for every miss, one is placed correctly..especially important if you don't want creaky floors. Others may have a different opinion on the 3/16 gap..but since it is a sub floor, that wouldn't cause me a lot of lost sleep.
A few missed nailings is to be expected; however, a lot could indicate the builder is not as experienced as you may want. As a military officer I used a technique for doing inspections that I found very useful and often use today. Do your walk through looking at everything but being detailed in a few highly important areas. If during the walk through you find problems (as with the nails) it is time to become more detailed in everything. Finding the poor nailing could lead you to more and larger problems. The proper nails, properly spaced, and properly imbedded is very important. A poor job will haunt you later. As stated point that out to the GC and – YOU along with the GC, do a detailed inspection of the entire project.