I rewatched the 3000m relay a couple of times... and again I cannot understand the ruling. The f***!
Edit: okay, Canada supposed obstruction at the very end was indeed stupid but not as bad as I thoght. The chinese skater in the last sprint puts her hand on the korean, true, but it doesn't look like it really affected the outcome of the sprint. BUT, not only the korean's fall clearly made the canadian fall, but also I could see that a korean skater which gave the change previously CLEARLY obstructed the italian, causing the italian to lose a good 3-4 metres.
Okay, let's forget the fall, but how about the obstruction? That was way worse than the canadian at the end (check it, 3:27 into the race).
I checked the medal count and I was quite surprised to see Korea with so few: only 7 total and 3 golds (before the 3000m relaxy); on the other hand they had multiple letdowns, especially in the short track where they are usually the leaders. So I guess the "home factor" played quite a role in this.