Something that puzzles me a bit is why when the Senshi go to 30th Century Tokyo, everyone addresses everyone rather more formally than they normally do. I guess it must be the way French people behave when you forget about tu and just call everyone vous which I can say from experience with trying to learn French these days is bloody annoying to keep straight. My best guess is that it is meant to lessen confusion in temporal issues, like how weird it would be if Usagi was constantly adjusting her verb tenses to deal with Queen Serenity or being weirded out at how when the two meet they forget that the image of everyday they normally see everyday is mirrored and this doesn't happen when you see someone face to face.