As Mulder and Scully are driving toward the abandoned building, the lock on Mulder's door is, between shots, open, then closed, and finally open again.
During the autopsy of the Fourth Victim, the depigmented corpse can be seen swallowing. Additionally, actual depigmentation would look much different than what is obviously applied make-up. Also during this scene, both Scully and Mulder are without any protective masks while investigating a suspected contagious disease and Mulder is even snacking on food.