The most common injury during a fight is broken knuckles, from people who don't realize that their opponent's head is hard. The second most common is a sprained wrist, from people who don't realize that their opponent is not going to go flying backwards after impact. This is why videos like "Gun to the side of the head" make me wince.
On a similar topic, don't try to break a beer bottle if you're in a bar fight. I just did research on this subject, and of twenty-four bottles, not one ended up as a decent weapon. Mostly, I just had lots of glass going every-which-way, and a piece of the neck of the bottle left in my hand. Seven of twenty-four times the neck was long enough to be used to cut, while not adding to the range of attacks. The rest of the time it was useless, especially if one were not (as I was) wearing thick gloves. And eye protection. Safety first!
UPDATE: I should mention that I really like "Choke from the front".