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Continuity: Episode 4.06, "Imaginary Friends and Enemies" - In the scene in the woods where we first see Owen's ghost, as the camera cuts back and forth between Melinda talking to Owen and what her friend sees, the two women are alternately closer and then significantly farther apart. They're supposed to be standing basically in the same spots, only taking maybe one or two small steps during Melinda's conversation with Owen.
Continuity: Season 4, Episode 23, The Book of Changes. When Eli tries to use a card to open Zoe's door, the card breaks. He is holding on to the larger piece of the card in his right hand when this happens and the smaller piece is in the frame. He gets the other piece and the shot changes to him suddenly holding the smaller piece in his left hand, as well as the card having been flipped around (the strip is seen in both shots, and the two shots face in opposite directions).
Plot hole: Season 4, Episode 7. Threshold. Jim taking over Sam's body just doesn't make any sense. It's plausible for a spirit to temporarily take over a living body, but a dead body is dead for a reason. It can't sustain life anymore. Death isn't a temporary ailment. It's permanent. What should have happened was the same thing that happened when another ghost took over a recently deceased person, which happened in a previous episode. The dead body would decay and start to lose function. Sam's body suddenly gaining back the properties of life is completely inconsistent with what we're led to believe in the setting of the show.
Continuity: At the end of the show when Jim is making toast they show him through the window taking the toast out of the toaster and putting it on the plate. In the next shot he is walking towards the kitchen table and the plate is empty. Then while talking to his mother he picks up a piece of toast to put jelly on it.
Other: Episode 22, Season 1, titled "The One": The captain talks about the "outflow valve", which has a distinctive rectangular shape and is fitted flush with an opening in the aircraft skin. It would be immediately recognizable by any crew member because it part of the walkaround inspection before each flight. He is holding a round pneumatic supply valve instead, which is part of the internal ductwork.
Factual error: Episode 22, Season 1, titled "The One": The tail section of the crashed plane is from an early model 737, based on the curvature where the forward edge of the vertical stabilizer meets the top of the fuselage. The maximum seating capacity would have been about 130 passengers, while the number of crash victims was given as approximately twice that.






