Towards the end of this episode, when asked about the cross Scully wears, Dana's mom states "I gave it to her on her 15th Birthday." However, a flashback in a later episode reveals she actually received it as a Christmas present.
The cable car ride to the summit of Grouse Mountain in British Columbia (here standing in for Skyland Mountain in Virginia, which has a slightly lower elevation) takes 14 minutes. Factoring in the delay caused by Krycek in the story, Mulder's ascent still would have only taken maybe 30 - 45 minutes at most. However the overhead sky changes from full daylight as Mulder boards the cable car, to blazing orange sunset when the car is halted on the way up, to nighttime darkness when Mulder disembarks at the top.
The car driven by Duane Barry changes depending on the scene. It is initially a 1986 or older Pontiac 6000 (almost vertical rear window, sealed-beam headlights), but changes to a 1987 or newer model during the drive up the mountain (bulbous rear glass, one-piece aerodynamic headlights).
Virginia doesn't have a highway patrol; its equivalent force is called the State Police.
In the closing credits, William B. Davis' name is displayed as "William B. David"
No it doesn't. It is displayed correctly: William B. Davis.
Despite supposedly being near a small town, the Vancouver skyline is plainly visible while Mulder is riding the car up the mountain.
If the maximum safe speed of the cable, for the cable car is 15mph, there would be no reason for a functional setting of twice that speed on the controls.
The ad that Mulder finds says Skyland, but when Alex is talking on the cellphone he says Skyline.