When the power goes out in Jason's house as they are watching the home movie, Liz takes the film reel from the projector. However, since the film was only half watched, a good portion of it was threaded through the projector. Liz didn't have enough time to remove the film from the threading and rewind it onto the reel in the time depicted on the screen.
The telephone handset in the introduction (set in 1963) has an RJ11 jack. The RJ connections became prevalent starting in 1973.
All or most of the home movies depicted in the film (including the "conspiracy" film) are in the Super 8 format, as evidenced by the larger center spindle hole and smaller sprocket holes. However, as all of the movies are dated from 1963 or before, they should be standard 8mm (smaller spindle hole, larger sprocket holes). Super 8 wasn't introduced until 1965.
How was the movie's lead character even born when it looked like her mother was killed by her father in 1963 which was before she was even born. She would have been very young then and was not in the house at the time of her mother's death and there is also no indication of who would have raised her .