Those on-screen beers that Ennis drank in the Riverton Apartment while waiting for Jack to arrive, did he chug-a-lug them or did he take his time drinking them?
In the book, Ennis is apparently completely sober when Jack finally shows up in the late afternoon after Ennis waited all the day long. Annie Proulx has Ennis mentioning going out with Jack and getting drunk, as opposed to Alma's idea of going to a restaurant/cafe to eat. And, in the book, it was Jack who ran up the stairs to where Ennis was standing.
I love the fact that Ennis was sort of like a kid anxiously waiting for the delivery of a coveted toy at home to come by parcel post. That is implied in the movie and in the book, too.