The thing that bugs me is that its nearly always the opposition team that puts the ball out when a player is injured. I'm sure that if someone carried out a statistical analysis, over 80% of the time the opposition puts the ball out. When its one of their own players who is injured, teams will carry on playing unless its obvious that the player is really badly hurt. You also find that if they carry on playing when one of their men is injured, and then lose possession, they will then start gesturing to their opponents to put the ball out.
Unless its a Buust type injury, leave it to the ref.