Nah, they're attached pretty low down. Check out the cross sections here: http://i.imgur.com/bJ4uEEh.jpg Real life strap-ons are often higher up for structural reasons, but in this particular fantasy universe strap-on technology is highly advanced.
So, could it be interpreted that the line of saliva dangling between Allison's mouth and the tip of her mistress' strap-on cock indicates that she was busy greedily sucking on her own pussy juice coating the shaft of the dildo, or is her stunned expression in reaction to her mistress ejaculating a load of cum in her mouth from the head of the dildo turned real cock?