The blood drop on Mike Ryerson's pyjama top changes. When first seen (when he is newly dead) it is a large spot on the pocket. Later, when he visits the doctor, the spot is nearly invisible in some shots. In other shots it is a very small drop slightly above the pocket.
After getting a visit from the vampirized Danny Glick, Mark is backing away from his bedroom window with a cross held in his outstretched hand. He then pulls the cross to his chest. In the next shot, his arm is still stretched out in front of him.
When Straker drives to the police station with his two suits, the rear side window on the driver's side in rolled down. When he arrives at his shop across from the police station, that window is rolled up.
The house that is burning at the end of the film in no way resembles the Marston house we see throughout the film. The burning house has a large colonnade entrance with a triangular roof and rounded corner sections.
In the Marsten House, Straker picks Bill up with his his hands on Bill's arms, just below the shoulders. But as he approaches the antlers, Straker has one hand on Bill's arm and one hand clutching his tie.
In their initial dinner in the bar/restaurant, Ben tells Jason that he left Salem's Lot at the age of ten. Later, as Deputy Nolly relates the information he got about Ben's past from the FBI to Parkins, he states that Ben left at the age of eleven.
When Straker is driving to his office to drop the suits to constable's office, the camera is reflected in the co-pilot side when the car is passing-by on the street.
Also after he park his car, the camera is again reflected in the pilot's door when he open it.
In the meeting with Mark, his parents, and Father Callahan, Barlow (the vampire) simply breaks into the house without any invitation by its occupants. All of the other vampires in the movie need to be invited in. However, Barlow is a powerful master vampire for whom such "rules" may not apply. Note how he doesn't recoil from Father Callahan's cross? In fact, he actually touches it and throws it to the floor.
After Danny Glick visits Mark outside Mark's bedroom window, Mark shows Danny the cross he took off the model on his desk and tells Danny to "Go away!". As the vampirized Danny begins to "float" backwards away from the closed window, you can see Danny is sitting in a chair on a boom that is lifting him away.
During the complete 184-min version, you can see Ned and Mike pushing the supposedly heavy and cumbersome crate towards the lorry - unfortunately it snags on the floor on the way, tilting upwards in a manner characteristic of light, empty crates.
When Mark goes to the Marsten house to kill Barlow, he pulls out two lock picks from a small case in order to break in. Then he clearly inserts the handle of one pick into the padlock, rather than the toothed end.