It has at least a two piece back (you can see the horizontal seam) so it isn't one of the repros. That said, who knows who made it!
If not a costume shop, I'd say L.L.Bean with the double seam pocket, single seam pocket flap, hand warmers, cuff and collar design.
Not a great fit - look at how wide the shoulders are - the seams fall on the upper arm.
This guy is civilian and not AAF, right? Those details make it much closer to what a civilian would really have worn at that point than a repro. I like that, shows real attention to detail.
You might try sending the question to the costume designer. She is listed on the IMDb page. I'm not that bold.