Hey gang,
I can almost positively confirm that they used an existing deck of Zener cards for the movie.
Back in May of this year, I purchased a vintage deck from eBay.
The 'bicycle' face of the cards was black instead of blue, but check out the faces!
The 'couple of wavy lines' card is flopped mirror image from the movie... well, they probably ALL are, but as it's the only asymmetrical design, it's the only one noticeable.
Here's the deck showcased in video, with a vague mention of possibly scanning the blue-backed deck and the faces of the black deck and having a set of cards printed.
What I didn't even remotely imagine at the time was the brilliant suggestion DD28 made in this thread months earlier, about the blank jumbo cards available at magic supply houses.
I found this thread again a couple weeks ago and it reawakened the desire to scan/flop/print my own movie-accurate deck.
Alas, I already wiped out the place he linked above, got the last 17 blanks they had in stock.
Currently awaiting some more from a slightly more expensive place, but they seem to be overdue.
Wish me luck!
Alex