well many things are shown to us, not clearly, but we can draw our own conclusions and make our own theories from them
first of all:
it seems the power of geass is known to the emperor of britainia and it may be because of VV. also right before Lelouch used the Geass on that guy, the guy said, "what? dont tell me..." so he probably has some idea of Geass.
another thing is it seems Suzaku won that gun duel cliffhanger and "erased" zero while keeping lelouch by most likely using VV to erase Lelouch's memories which CC triggers back by her kiss.