The rules of hockey are becoming less and less clear by the year. Fans and players alike don't seem to know the rules are and with every passing season, the lines get more and more blurred. One rule that is usually clear though is when a goaltenders mask comes off the play gets blown dead, but after you see this you might rethink that as well.
Take the Fall Classic for example in which Dubuque took on the U.S National Development Program. Dubuque goaltender Kevin Reidler seems to have a loose mask and takes it off while the U.S is on a breakaway, Brodie Ziemer scores, it is ruled a goal on the play and then overturned; take a look.
Normally, if a goaltenders mask falls off, the play is blown dead, but it's not every day you see a goaltender purposely take his mask off.
It didn't really end up mattering for the U.S however, they did go on to win the game, but this was definitely a weird situation.