Something that's really bothering me
During much of the movie when Poirot talks, his mouth isn't visible on screen. Usually, his face is turned away from the camera and it's very distracting. I don't like Finney's accent in the first place, and that combined with not seeing his mouth move is making it seem like a really weird disembodied thing.
Overall this is one of the most poorly edited films I've ever seen.