Continuity mistake: When Robin is burying his father, he cuts his hand saying, "I swear it by my own blood" and that he will avenge his fathers murder. We see the blood dripping over his fingers. Suddenly the camera shot changes and Robin's hand has no blood seeping between the fingers.
Continuity mistake: When Robin reaches the cliffs after escaping from prison, he jumps out of the boat and starts kissing the ground. He then reaches out with his right hand for help up, but when the camera switches, he's being lifted by his left.
Continuity mistake: When Robin heroically swings across to Fanny and the child in the Sherwood Forest battle scene: He swings straight across, with the rope's focal point fixed between himself and Fanny. Then he gives the rope to Fanny to swing across to John. This time the focal point is between her and John. Someone somehow managed to "move" the rope in order to move the plot along. That was jolly nice of them wasn't it?
Continuity mistake: At the start when Azeem is tied up in the prison, at one point when he asks the Christian to free him, his hands are tied at the wrists, then apart tied to the wall, and then back to his wrist all in three quick takes. (00:05:15)
Continuity mistake: When Robin reaches his homeland, after he kisses the ground, he rolls over in the water. His coat is covering him, then in the next scene, it isn't, then it is, then it isn't. (00:12:15)
Continuity mistake: When Azeem first blows something up, the Friar is next to him and Will, Robin, John and Bull are seen behind them around the model of the castle. However when it goes to the next shot there's only Will and Robin around the model. John and Bull walk in a few seconds later.
Continuity mistake: When Robin goes to the Church, the camera pans down from an enormously high vaulted ceiling in a vast cathedral. A few moments later, Robin and the Sheriff come running out of the Church and it's a small little stone shack.
Continuity mistake: At the execution scene where Will Scarlet is about to be beheaded, Robin picks up a burning arrow to shoot the executioner. When the arrow is first picked up from a dead body, the flame is half-way up the arrow, but when Robin fires it, the flame is (conveniently) at the arrow's tip.
Continuity mistake: When Robin first goes to visit Marian, he enters the house with a roll on his back (over the shoulder). It's there when he enters and the maid tells him to 'stand right here'. A moment later "Marian" appears, and the roll is gone, it's not on his back, or even in a wide shot showing he took it off. It never appears again.
Continuity mistake: Throughout most of the film, Robin wears brown boots with metal studs around the calf. When he is fighting the Sheriff of Nottingham at the end, he is suddenly wearing greyish boots, with cross-garters. Since you see his brown boots just before he enters the castle - when he kneels down near the dung they're especially visible - it is rather ludicrous that he would suddenly change them, given that he is rushing around trying to save the other outlaws, and then Marian.
Continuity mistake: When Marian and Duncan leave the camp by boat, Marian's lady-in-waiting, Sarah, is nowhere to be seen. Surely she should have left with Marian, as she is with Marian later in the chapel.
Continuity mistake: This mistake makes sense only if you've seen the extended edition. In a deleted scene, it is understood that the sheriff cuts out his scribe's tongue. In a later deleted scene, the scribe has to write messages on a chalkboard to communicate. Later still, at the end when Robin and company invade the castle, Robin asks the same scribe where the sheriff is and he verbally tells him, "Up the stairs," or something similar. Maybe he could speak a little, but he wouldn't have been able to pronounce the letter 'T'.
Continuity mistake: When Robin and Azeem are approaching Dover Beach, there is shot behind the boat showing only one sailor standing at the stern. In the very next shot, not only is the sailor standing but suddenly so is Robin, at the bow.
Continuity mistake: When Robin is challenged by John Little after attempting to cross the river watch Johns staff. The scene cuts between shots from in front of and behind John. All shots from in front of him show him leaning closely on the staff, all shots from behind show him holding it to side and not leaning on it.
Continuity mistake: When Robin is talking to the Bishop about his Father, they are in a small chamber in the Church. Later on in the film, when the castle is being stormed, Friar Tuck enters this room and throws the Bishop out of the window. Only this time the exact same room is in the castle, not the Church.
Continuity mistake: In the big fight scene in the forest Robin is not wearing his necklace. But when he goes to help save Fanny before he swings across the necklace suddenly is around his neck. (01:39:40 - 01:40:25)
Continuity mistake: Guy of Gisbourne's men come upon two of Robin Hood's men in the forest, trying to pull a log onto the path. The men see their enemies and run away, leaving the log sticking out onto the path. But the log suddenly disappears when Gisbourne's men go after them, and never again reappears.
Continuity mistake: When Will tells the sheriff he'll have to "respectfully decline" his execution, from one angle his hands are behind him holding onto the gallows, but from another angle they're outstretched.
Continuity mistake: During the hanging scene, when Bull cuts the rope to close the gate, he cuts it and runs so he doesn't get squashed by it, but in the zoomed out shot, he is suddenly on the ground and rolling away. (01:57:20)
Continuity mistake: Just before the 'one true weapon' speech, one of the villagers shows Robin what the soldiers did to his son, Will walks toward Robin and pulls his dagger from its scabbard, after Azeem says 'if it's fame you seek.' the camera goes back to Will and he is no longer carrying it. In the behind shots, it can be seen back inside its scabbard. (00:55:00)
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.