I remember reading somewhere that the Gregorian calendar-based Easter date is way off from the truer dates. The Eastern-rites Catholic church, Eastern orthodox church follow the older Julian calendar that matches the Easter date each year with Passover on Jewish calendar, which makes the date in theory much more accurate.
And in addition, even the dates of Jesus's death and resurrection are off: one source says Jesus died on a Wednesday and resurrected on Saturday. <><
