Neils shack No Snow Globle cart complet that quest, also the train tunnle just off the air force base when u get to the door and enter it u just go throw the floor and cart get back as u just fall into nothing ness

There is no snowglobe in Neil's Shack - there are a total of seven of them in other locations (eight if you have the Dead Money DLC).

Your second item - this is a glitch that happens sometimes when an area doesn't load properly (I've had it happen in Goodsprings). Reloading a previous save (or fast traveling away from the area and then coming back) should fix this for you.