Tell you what, this hardly qualifies as a "production mistake," but the preceding posts have reminded me that I've secretly--or maybe not so secretly--harbored the suspicion that the real reason we see Jack warshin' those clothes wearin' nuthin' but his boots (though we don't really see anything) is because we've already seen Ennis warshin' ever'thin' he could reach wearin' nuthin' but his hat (though we don't really see anything there, either).
In other words--one star gets a nude scene, the other one has to have one, too.
Same deal with seeing both Michelle and Anne topless. One has a topless scene, the other has to have one, too.
Ooops, do I sound cynical?