When he is first seen, when he rides through the gate, when he arrives and departs from the fight, and when he approaches Camelot, Caliburn is gray instead of black.
When Valiant is riding down the road and calls to Denys in the back of the wagon, nothing but the landscape behind can be seen through the screens of the cages stacked behind him, but when Denys rises, he suddenly can be seen through them, meaning he should have been able to previously as well.
When the robbery-victim is first shown being approached his tunic is green, but when his wallet is cut away the tunic it was shown against is red.
When Valiant accuses Denys of preparing to take Caliburn, he is shown walking to Denys' right, but in the next shot he's standing before him again.
When King Arthur first speaks to Denys, he has just stepped forward from where he was next to Valiant, but in the next shot is beside him again.