Before I look at my copy of the DVD, I will tell you what I think it is. Being a filmaker, there are hints in the movie.
It is divorce papers for Bettina.
Chuck mentions this when he was complaining to the Russians for their slow delivery. "This could be someone's legal papers." Also, the delivery was to the bad cowboy husband with the honey. "It's from the wife." Then he ads to the delivery boy. "Come back later and I'll have a package for you." In other words, give me time to go over the details, I'll sign it and send it back to the wife. This then opens the door for Chuck and Bettina to get together. After all, both are Elvis fans.
You will also notice something very funny. Notice the name on the gate entrance at the beginning of the film. Then look at it at the end of the film. Betina took the liberty of cutting something off. Oooh owwww.