These are movies that are listed elsewhere online as polyamorous movies. I have not seen these, so I'm making a list of what I should watch, to verify for actual poly-ish content & possible addition to the verified Poly-ish Movie List.
This list is extremely dubious - most of them sound like nothing more than cheating or casual sex movies. I do not recommend trusting this list as a poly movie list. Also, this list is in alphabetical order by American or English title (if it has one), so if you see a foreign film that looks out of order, that's why.
Angels of Sex
And Then Came Lola
Anna and the King of Siam
Anna and the King
As It Is In Heaven
The Avenging Angel