Here's Bag 1!
I put on some good Christian music, made a big pot of coffee (I drank six cups) and spent three enjoyable hours assembling the first bag.
As with my other two Lego trains, I kept thinking that parts were missing. If that happens, just start sorting everything, and the part will turn up. I have never bought a Lego set yet that was missing any parts.
As they often do, Lego included a few extra tiny parts. Because I was careful during assembly, I know that I didn't miss anything.