Richard Burton and the Roman Ritual
In Exorcist III, the only real saving grace of the tacked-on and out of place exorcism scene at the end was getting to hear Nicol Williamson recite the Roman Ritual.
I felt short-changed by the fact that we don't get to hear Richard Burton doing the same in EII. With his famous voice and gift for "literary" recitation, it would have been one of the few bright spots in this film and an offset to the fact that he otherwise phoned in the rest of his performance (to put it generously).