Usagi and Minako are watching skating on TV, and Luna and Artemis suddenly mention that figure skating was a big thing in Moon Kingdom culture. We promptly cut to Kunzite announcing that he’s going to use that to attract and identify Sailor Moon.
Given the canon explanation for why none of these people are a hundred percent sure what they’re doing on their best day, this is actually pretty believable. One of them has an experience that recalls a memory, and when it arrives, the Silver Crystal’s ongoing system-restore process copies that packet and uses the keywords to do a quick-and-dirty targeted restore on everyone else’s memories of that topic. Boom, collective mnesia.
I wonder if that’s ever happened to them before. Like, Usagi starts talking about the cherry in her sundae, and then suddenly Luna remembers how the Moon Kingdom got cherries shipped over from Earth because the trees wouldn’t grow there, and the next day Jadeite is giving out free samples of energy-draining cherry desserts at the supermarket and Sailor Moon has to beat up a cherry youma.