Factual error: When Mulder wants to shoot the third resurrected agent, it turns out that there is no ammunition left in the revolver. In fact, there should be one bullet left. When Frank Black takes the handgun from the necromancer, one can see that the cylinder is full with six bullet. Then, he fires three bullets into the first resurrected agent and two bullets are fired by Mulder into the second resurrected agent.
Continuity mistake: When Skinner walks away from the conference table, his armchair is only slightly turned left from its normal position towards the table, but when he comes back with additional documents, the armchair is turned left to the position perpendicular to the table.