I think you can see from these two slides why the drain plug looks like it does:

 

Thanks for posting that. I see the drain plug but don't understand exactly what's going on there as the O-ring at the tip is so high up. How does the oil drain completely from the oil pan? It looks like the bottom of the pan is much lower than the O-ring.

 

When you remove the drain plug, there is nothing to stop the oil from draining. It appears that the upper o-ring keeps oil from draining from the sump tank into the oil pan during normal operation.