If you go off the map you should be killed/eliminated instead of respawning. This can be exploited--if you lose health you can fly off the map, respawn, and have perfect health again. This obviously defeats the purpose of having survival mode enabled. inf_Abel and inf_Warehouse are prime examples of where this can be put into practice.

On a similar note, if you change teams in survival mode, you should have to wait until the round is over instead of just spawning on the new team immediately. Again, this is a potential exploit--if you lose health you can simply change to the enemy team then change back again and have full health again.

If you turn survival mode on, win a round so it says "You have survived" and quit, then turn survival mode off and start a new game, the green text will remain at the top.