Continuity mistake: When Mulder and Scully are moving into the house, there is a shot of Mulder's watchface which reads that the date is the 7th. A few minutes later, Scully is walking around with a video camera, and narrating and she says the date is February the 24th. (00:08:35 - 00:09:30)
Continuity mistake: When Frohike plays the slot machine, the first position on the reel shows a single bar. After Byers spots Suzanne, the camera goes back to Frohike and the first position now is not a single bar. There wouldn't have been enough time between the shots for Frohike to have another pull of the machine. (00:10:15)
Continuity mistake: During the conversation with Scully regarding Wayne Weinsider, Mulder says "I don't know why. I'm not a psychologist", which must be a big surprise for all viewers, to say the least. Mulder graduated from Oxford University with a Bachelor of Arts degree in Psychology (e.g. "Dreamland II") and he worked for some time as a profiler for the FBI (e.g. "Young at Heart"). (00:32:25)Chop Luftmysza
Continuity mistake: At Mulder's 'funeral' around when there is a knock at the door, we see Frohike raise his bottle to take a swig. The shot cuts to facing Scully and we can see Frohike further in the background and his bottle is nowhere to be seen, when he should've been mid-swig.
Continuity mistake: When doctors make a cut on Cassandra's belly, the green substance comes out of the cut and pours down directly onto the piece of blue cloth she is covered with. In the next shot the fragment of cloth that was in contact with the substance is dry, but in the following shot, there is a large soaked stain on the piece of cloth. (00:00:50)Chop Luftmysza
Continuity mistake: Malcolm Wiggins stabs Alfred Fellig in the back three times, including once in the middle of his back to the right of his spine. However, when Scully is examining Fellig's back later in the episode, he has at least six stab wounds, and all of them are around his shoulder blades. (00:13:30 - 00:18:00)Phaneron