These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Critical Research Failure: Virtually every claim made related to Catholicism is the opposite of how it's actually practiced. For example, the priests claim at one point that a possessee would not be repelled by inverted crosses, as they are blasphemous symbols — forgetting that an inverted cross is actually known as a "Petrine Cross", a holy symbol associated with Saint Peter (who apparently requested to be crucified upside-down, feeling himself unworthy to share Christ's death) and his successor, the Pope. At another point, they claim that it is important to recognize the identity and infernal rank of the demon, when the Catholic guidelines are to completely avoid playing into the demon's ego and simply treat it as "the devil, an enemy of Christ".
Ham and Cheese: Susan Crowley as Maria Rossi, one of the few lauded elements of the film because many found her over-the-top possessed antics entertaining.