I beg you!! Add to all factories a small icon, which shows where the exit!! I always build a building facing the wrong way, and my units get stuck. Symmetrical building is difficult to see where the front where the backside.
I hope you realise that units can exit out of two (opposite) sides, right? Give the factory a rally point away from where things are getting stuck.
When you're building it some nice big arrows that show the exit ramps would actually be quite nice, not necessary for experienced players but wouldn't get in the way so I don't see why not.