MKS EZY models has circlips to prevent unwanted removal.
Although most folks don't bother using them; myself included.
No problems for the most part.
MKS EZY Superior models require that you line up dots before
they will separate. Making accidental(and/or intended) decoupling
harder:
MKS ESPRIT SUPERIOR PEDALS by
1nterceptor, on Flickr