In the original series, Luna and Artemis never went to the Moon to plead for Queen Serenity's assistance but stayed at Usagi's home on Earth. Also, the two felines never possessed any long-distance teleportation abilities.
When the Inner Sailor Guardians attack Queen Metelia with Sailor Planet Attack and it fails all of the Inner Senshi Eyes were completely white. In the Viz Media English dub, their eye pupils are added.
In the original series, Prince Endymion was not protected by the spirits of the Four Heavenly Kings but was killed by Queen Beryl in the lair of the Dark Kingdom.
Sailor Moon and Tuxedo Mask were not absorbed into the increasingly dark energy of Queen Metalia in the original series.
In the original series, The Silver Crystal never changed into a flower shape but remained orbicular.