I feel there were a lot of times where units inadvertantly friendly fired in this game. Sonic cannon from archer in general, and there's one time in particular where I'm dancing a duck around the factory and ripper keeps predicting the movement and shooting straight into it's own factory.

EDIT: I come bearing a video of the incredibly egregious friendly fire incidents. I think it has to be an engine bug, the second one looks like it was trying to attack around just the west facing polygon from the factory.