Continuity: Jeremiah Smith and Mulder are with the kids, and in the background, when CSM is looking through the window, Samantha's clone and the other kid disappear.

Continuity: Scully tapes an X in the window,that X changes shape when Scully is talking to Mr. X and before Mr.X dies when he checks on the apartment.

Continuity: Scully was bound with tape to the chair, but in the last scene she gets out of the chair after Mulder frees her hands, but without freeing her legs.

Revealing: When Mulder and Scully enter the doctor's house, you can see over their shoulders that it is showering with rain outside, yet both of them are bone dry.

Other: In the episode "Musings of a Cigarette Smoking Man," when CSM is writing his letter of resignation on his typewriter, you can see that the letters are already there - he is simply typing over them.

Continuity: In other episodes the name of The Lone Gunmen's newsletter is "The Lone Gunman", but in the shots of their office door it has a sign saying "The Lone Gunmen. Publishers of 'The Magic Bullet' newsletter."

Continuity: When Scully finds out about Betts' mother she says that "She lives right here in Pittsburgh." Nothing wrong there except that at the time they has just left Chuck Burks' lab - which is in Maryland.

Visible crew/equipment: When Ed turns to go into the office, you see the reflection of the boom mike on the glass window.

Other: When Mulder opens the body bag containing the "partial" remains of Max Pfennig (AKA Paul Gidney) a pulse can be seen beating in the right side of the corpse's neck.

Plot hole: Scully's statement that she was 23 when she wrote her senior thesis in college throws off her timeline of college, med school, residency, FBI Academy, Quantico teaching assignment for two years, and X-Files assignment at 28. Her undergraduate degree in Physics should have been completed when she was 20 or 21 to allow at least 4 or 5 years for her medical training.

Continuity: In the shot of the 6th Precinct police station, it has a California state flag flying out front. The episode took place in Massachusetts, at the Massachusetts Institute of Technology.

Continuity: We see Scully wearing pants while sitting on the couch, but when the real Mulder comes in, she jumps up and we see she's wearing a skirt.

Visible crew/equipment: As Fox is being led into the jail, when Scully says, "Mulder" the boom mic is at the top of the screen, while she's walking towards him.

Factual error: The date stamp says that it is April 12 and Scully says that it is Sunday, but April 12, 1997 was a Saturday.

Visible crew/equipment: When Scully asks Fox "Do you know what day it is?" the boom mic drops down at the top of the screen.