I'm not sure how much of this in the EOC, but these are all inventions post canon:
Purgatory,the Mass, transubstantiation, indulgences, the treasury of merit, penance, the rosary, prayers to Mary, holy water, the papacy.
Take out the purgatory (the EOC teaches an intermediate state but is somewhat different from the Latin purgatory although convergence of these does not seem impossible if the terminology if refined), transubstantiation (too 'technical,' but the belief that the Holy Spirit changes the bread and wine into the Precious Body and Blood of Christ is the same), indulgences, and treasury of merit.
Orthodox penance is somewhat different from the Catholic one. We don't do 10 "Hail Marys..." Orthodox penence is a period of time the priest feels is needed for metanoia (change of mind), repentance.