This might be because anything after the original Ojamajo Doremi counts as a Post Script Season, but one thing that really bugged me was the Queen election system via the MAHO Dou. In episode 20, Majo Rika wanted to keep the shop because it's tradition that whoever owns the shop ends up becoming The High Queen of the Witch World. All of that is completely forgotten about by Sharp, where it's decreed that the babies born from the Witch Queen Rose will become the Queen, i.e. Hana. You could say that every millenia when this doesn't happen, people would probably use the election system but given the lifespan of witches, it doesn't seem likely.
Why couldn't the Ojamajos use the same spell they did when Poppu summoned ghosts at the preschool sleepover in the episode where Poppu becomes a witch apprentice (The spell was something among the lines of "Put everyone to sleep"), when they were found out to be witches?
Would Tamaki become a witch apprentice had she successfully said "Are you guys witches?" If not, who would?