After being seriously underwhelmed by the new take, I was knocked out of my socks by this episode. JLU has been terribly uneven with flashes of brilliance here and there (the Solomon Grundy ep comes to mind) but this has been the first episode that was just balls to the wall comic book goodness. I was sort of surprised that Batman didn't say something to Jonah Hex like he had heard of him before (from the BTAS ep "Showdown"). Nice to see future Gotham & Terry McGinnis again!
What's amusing to me is that there isn't an Elkhorn City in OK but there is an Elk City. Apparently there is an Elkhorn City in KY.
This episode pressed all of my geek buttons, though I mistook Pow Wow Smith for Scalphunter at first. Probably not an uncommon mistake since this episode was based on Justice League of America 198: I also thought this was odd, but it didn't bother me too much. I had hoped to see the Atom in this episode since Chronos was involved.
I think Bruce didn't mention having met Jonah because he wanted to avoid contaminating the timeline anymore than it already had been at that point. Anyway, he would also have to explain the whole Ra's al Ghul and Lazarus Pit thing, and that gets a little complicated.
And by the time it got around that Jonah knows about time travelers, they were about to get into the big action, and didn't really have time for a heart-to-heart about Jonah's future.
I thought about that as well, but then Batman could have just turned to GL or WW and mentioned it. Something like "Hey, I know this guy by reputation, he's cool." Because Bats and Hex never met if I remember the episode correctly. It was all a tale told to them.