When the ghost is taking over the computer in the basement, you see it locking down the exits including closing and locking an open window. However earlier in the movie it was stated that all windows were permanently sealed shut.
When the virus enters the computer system, Harris is sprayed with glass when one of the monitors explodes, despite the fact that most flat screen monitors do not have glass fronts. He also blinks after he's died and fallen onto the keyboard.
When a bleeding Moreton is dragged down the hall he leaves no blood trail. There's also no blood on the floor where his body fell.
At the beginning of the movie - "14 years ago" - when the girls are riding their bikes down the street towards the house, clearly modern, late-model cars are parked along the street.
After Paula Clark falls down the stairs Rudy calls her "Miss Cummings", the actress's name.