I have two soldiers with "reacton-fire" activated,the second directly behind the first one.
If an alien shows up,it happens from time to time that the one from behind shots onto the enemy but hits his teammember in the back,who is obviously in the line of fire:
[alien] - - - - - - - - - - - - [Soldier 1] - [Soldier 2,fires and hits Soldier 1!]
Is it a bug or a feature?