uglyraedII
If you are talking about possibilities, sure, anything is possible. Given the tensions in the region and the amount of military equipment, all scenarios are possible, although you can be sure that the US Navy has learned a few lessons from the USS Vincennes incident and has additional procedures in place to prevent another incident that won't earn public-relations points.
Likewise in Saudi Arabia. While "crime" in the traditional sense of the word is relatively low, I recall a Saudi Arabia from just a few years ago where there were attacks on compounds, bombings and well-planned killings. Also recall a number of raids by Saudi security forces, which netted a number of weapons caches. Like anywhere, there is a very small fringe minority in Saudi Arabia who wish to make a statement through violence. Unfortunately, neighboring Yemen provides a ready market for a wide variety of impressive weaponry-- you have the cash, they have the gun.
If we are talking about likelihoods though, that is a completely different issue altogether. Personally, I would be more concerned with the possibility of a few guys with a MANPAD in the trunk of their car at the end of the runway, as was the case with the DHL accident, rather than being the mistaken target of the United States military. In any case, I understand the US military has been confined to barracks and as of the last few days, the Iraqis are running the show.