Audio problem: During the scene of the birthing woman, Azeem says, "If you won't hear my advice...", but his lips don't move.
Audio problem: When Wolf attacks Will before the hangings, the guards pull him off and he says "Kill him." But his mouth doesn't move.
Audio problem: When Robin and his men have Friar Tuck pulling the wagon you can hear the men singing, but in the shot facing them, their lips are not moving.
Audio problem: When Marian is attacking Robin inside the house, and Azeem is trying to break down the door from the outside, Duncan says "Point me towards danger, Azeem. I'm ready." But his mouth doesn't move at all.
Answer: The white robes, reference to "the old ways", and pentagram across the map when the Sheriff meets the Barons suggests per-Christian Druidism; the upside down crucifix certainly implies Devil-worship. These two spiritual paths are, by nature, mutually exclusive. In short, a fictional pseudo-witchcraft invented for the film, yes.