Plot hole: Agent Spender watches in horror as Alex Krycek stabs the neck of an alien directly in front of him and the usual bubbling green blood spills out. In every other instance of a human being in such close proximity to the green blood, the person has immediately taken a painful reaction to the substance, including severe damage to the eyes. Spender however is completely unaffected, as is Krycek, who was also close enough to feel the effects.
Suggested correction: The Syndicate is well aware of the effects that the alien blood has on humans and the inherent risk of being exposed to it. They would have inoculated Spender and Krycek in preparation for this.
There was no inoculation ever mentioned to counter the effect of the acidic blood. Also, Spender wouldn't have let someone randomly inject him with something with no explanation, it would be completely out of character, and he was surprised at what happened.
Suggested correction: I think that this is to do with where he is hit. I don't recall anyone suffering the toxic effects when the weak spot at the back of the neck is successfully hit with the spike weapon. When Mulder tried to kill the alien bounty hunter (think it was in Colony?) He missed the weak spot, which is why the blood had an effect on him and the bounty hunter survived.
Clyde Bruckman's Final Repose - S3-E4
Visible crew/equipment: When the agent says "I'm Kline, this is Havez" the boom mic is by the light on the ceiling. (00:04:15)
Visible crew/equipment: When Scully says "This is rumor panic" you see the camera shadow following her on the lower left side of screen. (00:18:20)
Continuity mistake: In the scene where the Riley Animal Hospital sign lights up, the time comes across the bottom of the screen saying 6:21 p.m. The scene then cuts to inside the animal hospital. However, the clock inside does not read 6:21. It reads somthing roughly before 6.
Continuity mistake: When Mulder experiences his near-death trance state his body is lying, apparently lifeless, in a star spangled sky. As the camera tracks in on him the toes on his right foot twitch, just after Deep Throat begins to speak. The foliage covering his chest also changes position between shots. In the wide shot he is covered up to the armpits. But the first close up shows his chest is exposed. Then in later close ups it is covered again. (00:14:25)
One Breath - S2-E8
Deliberate mistake: When Scully is shown on her hospital bed, it's obvious she's wearing a bra under her hospital gown. It's doubtful that a patient in a coma would be wearing a bra as it could restrict her circulation.
Factual error: Atlantic City, New Jersey really doesn't have woods around it like it does in this episode.
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. (00:41:35)
Visible crew/equipment: In an early scene with Scully and Skinner talking in the hallway, there is a crew member obviously hiding behind a trash can. (00:07:10)
Factual error: When Reverend O'Connor is reading from the Book of Revelation, his Bible is flipped open towards the front. Revelation is the last chapter in the New Testament, so his Bible should have been open towards the back. (00:14:30)
Continuity mistake: Marita Covarrubias tells the tribunal that she used to be Special Representative to the Secretary General of the United Nations. However, in "Herrenvolk," she told Mulder that she was the assistant to the S.R.S.G. (00:39:15)
Continuity mistake: During the autopsy, Scully says that the date is August 29. The two previous episodes were set in September. (00:09:50)
Die Hand die Verletzt - S2-E14
Factual error: Mulder sees water going down the drain counterclockwise and says something is up since all water in the northern hemisphere drains clockwise. This is not true. Water can drain in both directions in both hemispheres. Things like convection currents, basin design, and residual swirl from filling the sink have a much greater influence. You would have to drain a small ocean to see the Coriolis effect, or use specially-designed test apparatus. See http://www.snopes.com/science/coriolis.htm and http://www.physics.ohio-state.edu/~dvandom/Edu/newcor.html (scroll down to *5.2. Water Going The Wrong Way Down The Sink* near the bottom of the page).
Audio problem: When Jerry uses the elevator, the voice of the computer reads out the floors as "twenty-third floor, fourth floor, fifth floor" etc, missing out the "twenty-" prefix until the 29th floor. The DVD subtitles list these numbers with their prefix, so this was not intentional. (00:21:10)
Never Again - S4-E13
Visible crew/equipment: When Ed turns to go into the office, you see the reflection of the boom mike on the glass window. (00:05:30)
Revealing mistake: When the doctor examine Ronnie's "corpse" in the morgue, he pulls out the stake. It is quite obvious that he's struggling with a wooden stake that is placed on the actor's side, not through his chest. Moreover, the camera pans up and you can briefly see Ronnie's unharmed chest.
Fresh Bones - S2-E15
Visible crew/equipment: When Mulder chases Chester on the pier, the camera's shadow can be seen as it circles around him. (00:25:25)
Continuity mistake: When Skinner walks into the cafe (the time he gets shot) another man is just walking out, leaving a table with a used glass and coffee cup. The waitress is in the back, getting Skinner a cup of coffee (she couldn't have cleaned the other table yet), but when we look over Skinner's shoulder you can see that the other table is cleared and has a clean coffee cup (turned upside down) on it.
