I was watching the movie again tonight and noticed a funny tidbit I didn't realize before.
The writings on the various postcards we see in the movie are carefully made to give the idea of not so well educated, "rough" people, and so is the one Ennis sends back to Jack to let him know his address in Riverton...
Well, of course, the one side we see already written with Jack's address and all, because the other side, where Ennis writes "You bet" in front of our eyes, is written with a completely different, and much contemporary calligraphy. Would this be eligible for the "goofs" section? :-)