I finally got the movement out of the case! With a good bit of forcing/twisting, I actually got the movement turned over enough (With the stem and crown still attached and through the stem tube) to get the stem retaining screw out. The stem looked normal enough, but it was a larger diameter near the crown and there was an o-ring at the base of the crown. Out of curiosity I held the flat end of the stem in a hand vise and was able to turn the crown section off. The crown has a short shaft of its own that is fitted with the o-ring and is female threaded at the end. The stem has male threads and the crown must be attached after the movement is installed in the case. The threads were tight all the way off so they must put some sort of a thread locker on when they screw on the crown to keep it from working off the stem during use. This watch was definitely designed to never be opened.
I did no appreciable damage to the case as the plastic is somewhat flexible. I'll see if I can get the movement cleaned up as it was only running intermittently before. It's small and brightly colored so maybe my seven year old daughter will like it.
Thanks for the advice everyone.