For Those That Were Confused (SPOILERS)
I came to this board to see what others thought of this movie and found massive confusion over major plot points. Some I understood the confusion over, others made it sound like people fell asleep in the middle of the movie.
SPOILER ALERT!
1) Mathilde was NOT shot by Pavel (or anyone else). Jack rigged the gun to misfire. They explicitly show him modifying the gun (even though Mathilde only wanted the scope adjusted) and give a good hint when he looks at it again before delivering it to her. It goes by fast, but they also show sparks and smoke coming from the back of the gun right after she pulls the trigger. The next shot of her shows a large wound around her eye. The same eye that was looking down the scope. It went by fast, so if you were in a theater it might have been confusing, but if you were watching at home and can rewind, it should be pretty obvious.
Why did he modify it? Either he realized it was a setup after he called Pavel to tell him he "wanted out" or he did it for more personal/emotional reasons (or both). If, at this point in the movie, you didn't understand that Jack is completely paranoid, I'm not sure if we were watching the same movie.
2) Jack was not the target from the beginning (if he is, then only Pavel knows this). Mathilde had multiple chances to kill Jack when they were testing the gun. It is presumed her target is someone else, otherwise she would have killed him by the river when they were testing the gun. It is not until Jack tells Pavel "he wants out" that we can presume Pavel wants to kill Jack and then tells Mathilde to do it. Mathilde was supposed to kill him when Jack gave her the gun, but "the opportunity didn't present itself" so Pavel tells her to find an opportunity, thus she is forced to try to kill him in the streets with the rifle. She shoots some woman to get into her home and quickly get to a high vantage point. When the gun misfires, Jack's paranoia is confirmed.
3) Jack asks Mathilde who her employer is and she replies "same as you" - now Jack knows Pavel is trying to kill him.
4) When Jack shoots Pavel, you hear three shots but only see two flashes from Jack's gun. This is a quick hint that Jack has been shot. At the least, you know Pavel got a shot off.
5) An aside about Roger Ebert's review: Ebert seems to think that Mathilde or Clara calling Jack "Mr. Butterfly" is some hint that one of them is going after him. I don't see this connection.
When Jack and Mathilde are testing the gun, a rare butterfly lands on Mathilde and Jack espouses his knowledge of butterflies (there is an earlier scene where you see him reading a book on butterflies). He also has a tattoo of a butterfly just below the back of the neck that Clara has seen. Both Mathilde and Clara call him "Mr. Butterfly" (although both appear to have valid reasons for calling him that). I'm not sure why Roger Ebert seems to think there is some special significance in Mathilde (or Clara?) calling him this. If you can explain this, I'm all ears. Although both of them calling him this add to his paranoia.
This isn't a debate over meaning or style, but just an explanation of plot points that are not open to much interpretation.