Was Habbershaw in on it?

I think it's because he sensed Meredith as an easy "mark" and a quick way to add to the pot. Ol' Meredith was salivating and just dying to get in on that table.


My "#3" key is broken so I'm putting one here so i can cut & paste with it.

No he isn't in on it. Two things make it clear why he let Meredith into the game. You'll noticed how "taken" he is by the beauty of the wife when he first sees her in the mirror at the bar and even to the point of not even hearing Fond speaking to him because he's obviously staring at her. Then later in the poker game Robards makes the point that he is known to be quite a playboy and the only reason the couple had been aloud into the game was he was looking to get "lucky" with the wife after the game was over.
After the reveal at the ends it all makes since that Fonda would target this particular player to get into the game because of his "background" with the ladies. Easy mark.

I wondered that too. Otto Habershaw just "happened" to be standing at the perfect place at the bar where he would see the lady perfectly framed in one of the bar's mirrors when she came out of their room. Not every room upstairs was likely to give him such a perfect look at the lady's reflection.

However, for this to be a setup they would have to know upstairs when Otto was going to be "stretching his legs" and exit the room just at the right moment. That was already a stretch (pun intended). But then too, even Habershaw had no control over what room they were given upon arrival. Still, it left me wondering if they had an "inside man" in Otto.

No doubt Habershaw's weakness for the ladies was taken into account - even counted on - when the scheme was in the planning stage. But for all the "happy accidents" that happened when they did to have taken place at just the right moment can best be put down to planning by the writer rather than by Habershaw.

When Habershaw wasn't sitting with the group dividing up the money I was pretty sure that he was as much in the dark as the rest. His being taken by the lady in the way that he was turned out to be just a plot device the viewer needed to get past in order for the story to unfold.