Continuity mistake: During the scene where Dr. Challis is at the bar and Ellie walks in to find him, look carefully as Ellie approaches Challis. In the long shot Challis takes a drag from his cigarette and is exhaling the smoke just as Ellie walks up, but a split second later, Challis is not blowing any smoke out. In fact, there isn't even any smoke around where he would have exhaled.
Continuity mistake: Ellie and Rafferty stand outside the hotel while Challis goes to check in. The sunlight is seen brightly shining on the windows of the hotel as Rafferty draws attention to Mr. Cochran's car. The scene cuts to an interior shot of Rafferty and Ellie as seen from Mr.Cochran's point of view inside the car. Looking at the windows of the hotel it's obvious the sun is at a different position from where it was just a moment before and, the light of day has faded.
Continuity mistake: Right after Ellie was kidnapped, Dr. Challis runs to a pay phone and dials the Operator to get help, and begins to state, "Operator." and gets a recording. Not only does he get a recording (which would be impossible in the real world), but the recording itself states, "Your call cannot be completed as dialed. Please check the number and dial again, or, call your local operator." Problem is - he was dialing the operator.
Continuity mistake: During the "test" on "little" Buddy, after the family has all been killed the camera switches angles from an in room shot to a monitor shot. In these shots it's clear "little" Buddy's legs have changed their position several times.
Continuity mistake: During the night scene where Ellie is walking back to the hotel room, a wide camera shot of the entire parking lot shows no cars (not even theirs) adjacent to the walkway. A second later, as Ellie gets closer to her hotel room, Ms. Gutman's car is now there and honks the horn at her.
Continuity mistake: After the old man is killed in the hospital, the killer gets into his car and sets himself on fire with gasoline. The car then explodes, causing parts of the car to shoot all over the parking lot. These car parts are on fire and surround the car, but a few seconds later they have disappeared.
Continuity mistake: Dr. Challis enters his ex-wife's home with his coat over his head from the rainstorm. His hair is slightly wet, but the coat itself appears to not have a drop of rain on it.
Continuity mistake: When Dan is peering through the ventilation grate at the control room, we see Cochran hanging up the phone. In the next shot (close-up) Cochran still hasn't put the phone down.
Continuity mistake: During the scene where Dr. Challis is outside talking to the bum, the camera shot from behind shows us Dr. Challis taking a huge drag from his cigarette as the bum is talking about Silver Shamrock having its "last Halloween." A split second later, the front camera shot now shows Challis replying to the bum, but no cigarette smoke is being exhaled from his mouth, as it should be.