Gael Clichy of Manchester City sustained an OBVIOUS head injury on July 24th in a match against the LA Galaxy. Initially he was removed, however not only did he finish the first half, he continued in the second half.
This is a classic example of a situation where an athlete should be removed and not allowed to return until cleared by a physician. Granted Clichy could have been cleared by a physician, any physician worth their salt when dealing in concussions would NOT have returned this individual with the mechanism of injury and immediate signs, forget what the reported symptoms were by Clichy.
As you can see in the video below the French player perhaps had no clue as to what just happened. Maybe there was a language barrier, again the SIGNS should transcend any foreign language. This is something that should not ever happen, had his leg been snapped in half would he have returned?
If this is to happen at a high school event and the player is not removed for the remainder of the game, then someone is in deep do-do.
Thanks to @ganglion11 for this example of horrible head injury management.