I believe the game vs movie issue will never end, and even some die-hard fans are willing to forget the existence of the whole movie and Pilgrim stuffs.
In my personal view, it's pretty hard to integrate the movie storyline with the previous one we've played and read. But then the movie itself is pretty much unique and quite a value to be neglected just like that.
Solution: Why not consider the movie an entire different universe or continiuum. But guess what, some people (like my cousin) believes that the movie version of WC was actually the WC Chris Roberts envisioned. Say, the intensement of the battle, the stress of war... the Kilrathi. Weren't those the way Roberts wanted them to be?