The plane is a Piper Comanche and too new for any of the original Indiana Hones movies, but could possibly work for crystal skull as it is from the mid 1950’s. This particular plane does have an explaimation though. It’s an art exhibit called “Avião.” Not nearly as exciting as ones imagination might lead them to, and sorry if that disappoints- but to those wantingo know- that’s what it is. It was shown in Buenos Aires a few years back.
It's the same dudes, those are (most likely) the inhabitants of the sentinel island, which is forbidden to try to visit or contact, by reasons you could probably guess o_0 :)
C'mon it'll be fun