I think I just spotted a tiny goof in the "happy tussle" scene. As they run toward the left of the screen, there's a horse standing there in the campsite. The horse leans forward to grab a bite of leaves or something, and I think I see a shadowy figure behind the bushes pull the horse back. So Ennis and Jack were being watched by someone at much closer range than Aguirre!
Has anyone else seen this? I was watching it on YouTube, with a small screen, so maybe I shouldn't trust my eyes. And imdb doesn't have it on its list of the movie's goofs (though I learned about a few on that list that I hadn't noticed and probably never otherwise would have!).