I loved the movie but the scene (or should I say the 2 seconds) of the death of the merry go round operator ruined it for me. It's so dumb. The movie makes such a big deal about killing people and how morally wrong it is, yet a policeman kills an innocent person and nobody talks about it ever again. I don't understand how possibly Hitchcock thought it was a good idea to put this into the movie. The death looks so unrealistic and almost has a comedic timing to it as if it was from a David Zucker or Mel Brooks film. It's so out of place and stupid I can't believe people don't talk about it everytime someone mentions this movie.
But why did the detective shoot anyway? Did Haines look so suspicious and dangerous that there was no other choice but to shoot him down? And how did the detective miss? Not only did he miss but the bullet went no where near Haines.
Why wasn't the detective worried after doing so? He's in serious trouble now for sure. He's not going to jail if he's lucky, but he's definitely loosing his badge. Imagine policemen having a right to shoot anyone they feel like because they are chasing a man who may or may not killed someone (even if he did kill his wife, he had a strong motives to do so. He wasn't a maniac. Also he wasn't armed. There were zero reasons for policeman to shoot and there were as many reasons to put this scene in the movie).
This two second long part of the film is so stupid I could talk about it forever. Who's idea was it? I wish I blinked when it happen. I bet thousands of people did, that way this movie is still regarded as an excelent thriller and one of the best Hichcock's masterpieces...

@ jktomas : yes you're kind of right about these 2 seconds, it doesn't ruin the film, but sure is disturbing.

Other scene that i didn't understand : why did Haines have to win the tennis game? couldn't he just loose to end it faster? Is the tournament really more important than his life???

Apart from some details absolute masterpiece in terms of mise en scene.

Classic Hitchcock. The shot of Walker in the tennis crowd is brilliant.