Continuity mistake: After the part where the head Kindred woman tells Mulder and Scully "I asked you not to interfere", Mulder leads Scully away. From one camera angle, he is leading her away by the hand. In the same scene, but from a different camera angle, he has his arm around her. When we go back to the first camera angle, he is once again leading her away by the hand. (00:33:10)
Continuity mistake: When Scully is reading report from Simmons' death, we can see that is has occured on the 7th of November, 1993; which means that whole episode takes place at the very beginning of November, but at the same time Scully and Mulder should be at Alaska (see episode "Ice"). (00:02:15)
Plot hole: After less than 1 minute of investigation Scully found out that the photograph was bogus. It tells a lot about the "very best" specialists, mentioned by the Deep Throat later on, who had prepared the photo. (00:19:10)
Continuity mistake: Near The End of the episode, Mulder is reviewing black-and-white photos of The Jersey Devil. A wedding ring is visible on The Jersey Devil's left hand in the photo. Earlier in the episode, she is not wearing the ring.
Revealing mistake: When Mulder and Scully are talking to Theresa at the diner she suddenly gets a nosebleed. If you look closely at her forehead/nose you can see the flesh coloured tube that pumps the blood. (00:33:20)
Factual error: When Mulder gives Scully the birthday card, she says that he is two months early. Given that Scully's birthday is on 23 February, the time of the episode should be sometime near Christmas. However, through the whole episode, there is no sign of Christmas time (not a single Christmas tree, no Christmas decorations, etc). (00:19:35)
Continuity mistake: When Scully walks into Mulder's office, she stops in the position with the "I want to believe" poster in the background, then she takes a couple of steps to make acquaintance with Mulder, and she finds herself again in the position with the poster in the background. (00:05:15)
Audio problem: The first scene following the intro, when Mulder and Scully step out of the car, Scully says, "I still don't get it" but her mouth doesn't move. (00:02:30)
Continuity mistake: When Mulder is at Ground Control and the woman is telling the space ship that they're going into fly-by-wire mode, the Mulder's visitor pass changes from beneath his jacket to above his jacket between shots. (00:20:00)
Continuity mistake: When Max bleeds out his ear, the blood stain on the pillow changes when Mulder and Scully see it. (00:32:10)
Other mistake: Eve 6 says that ordinary human beings have 46 chromosomes, while the Adams and the Eves have 56 chromosomes. This makes 10 additional chromosomes. However, Eve 6 also mentions that they have additional chromosomes number 4, 5, 12, 16, and 22 - only 5 additional chromosomes. (00:22:40)
Visible crew/equipment: After talking to the scientist about his car, Mulder and Scully are talking in front of a door. In the glass of the door is a reflection of a third person.
Continuity mistake: When they find the cocoon, the body inside is completely different in appearance from one shot to the next shot of it.
Deep Throat - S1-E2
Visible crew/equipment: When Mulder and Scully attempt to interview Col. Kissell, as he gets out of his car, you can see a square light reflector screen reflected on the car door. (00:12:37)
Continuity mistake: When Mulder and Scully are arguing outside the hospital, after meeting Billy and Peggy, there is a woman in a red coat, behind Scully, who gets out of her car and then vanishes between shots. (00:19:30)
Continuity mistake: During the Re-qualification practice shoot scene Dupre as agent Willis fires until he suffers a failure-to-eject stoppage (stovepipe), despite staring at the ejection port throughout the preceding drill he fails to recognise and clear this (as any firearm user would, especially a bank robber with the partial memories of an FBI agent/instructor), and could potentially still have rounds in the magazine. At the next camera change the slide is fully back despite no manipulation from Dupre, as he removes an empty magazine. (00:19:01)
Character mistake: Scully gives a description that Eve is driving a Blue Carolla. However in the next scene, Eve is driving a Pontiac, not a Toyota. (00:28:00 - 00:28:51)
Factual error: The local Pasadena station code is WXDL, however it should start with a K not a W. (00:00:05)
Continuity mistake: At The End of the episode, when Lyle is transforming in the bathroom, we see his hand perfectly shred a shower curtain, however in the next shot we see his hands and they are still fully human. There's no way he could have done that. (00:38:44)
Born Again - S1-E22
Continuity mistake: When Felder is being strangled to death by his scarf getting trapped in the bus door, pay attention to the bus driver throughout the sequence. He is a young black guy for most of the sequence however there is one shot from the front of the bus were you can see he has suddenly changed to a white man. (00:21:53)