As per Annabeth Gish (Reyes), the special effects for the birthing scene consisted of cottage cheese and strawberry jelly.
The car chase scenes in the FBI garage took four days to film.
When Agents Scully and Reyes arrive at their destination after escaping the pursuing Billy Miles, Reyes informs Scully that they are in a place in Georgia where Agent Doggett was born. Robert Patrick, who plays Agent Doggett, was actually born in Georgia.
Billy Miles' hand that punches through the elevator door was made of solid steel. It could have done some serious damage to Mitch Pileggi if it had hit him.