(at around 5 mins) When George is making scrambled eggs, the skillet on the stove has egg dripping all over the sides of the pan but when he picks up the skillet it's totally clean.
(at around 1h 16 mins) When Kathy and the kids are getting down from the roof after being chased by George, we can see Billy, Chelsea and Kathy get to the stairs in that order, leaving only Michael still on the roof. In the next shot Kathy ask Chelsea to jump because she's on the roof again with Michael.
(at around 53 mins) When George is chopping wood and Billy is holding the second log, George swings the axe back, and when he's swinging the axe at the log, that Billy is holding, he doesn't have the axe on his hands. The axe reappears when he chops the log.
(at around 1h 7 mins) When Kathy sits down in the library to read Chronicle of a Zealot she flips through the pages and you can clearly see that the pages are completely empty and appears to be from some kind of notebook. She then finds what she's looking and starts to read, the camera cuts to another angle and suddenly the pages are filled with old fashioned printing.
(at around 59 mins) At one point the Lutzes are in the kitchen and the refrigerator magnets read "Home Sweet Home". In a rage George knocks the letters down. In the next shot, the letters spelling out "Home" are visible in their original position.
Despite the fact that this was filmed in Super 35, "Filmed in Panavision" is listed in the ending credits.
(at around 7 mins) The actual address of the house when the Lutz family moved in was 112 Ocean Avenue. When George and Kathleen visit the house for the first time, the address is 412 Ocean Avenue. This is because not only is the movie not meant to be historically accurate in any way, but for legal reasons they were unable to use the house's original address. For the same reasons, the children's names have been changed from the original Lutz family names.
(at around 45 mins) After George visits the doctor, he and his wife drive past a building with what looks like a Starbucks logo, but in fact is a hair studio sign with the studio's name on it.
The shot of George breaking through the cement brick wall in his basement was done with bricks that were clearly only about an inch thick, allowing for a cleaner stunt.
At the 45:44 mark after George visits the hospital the Lutz's are driving home discussing the diagnosis but the screen shots clearly see the gearshift lever is at the 1 o'clock position on the steering column which indicates the truck is in park.
On the wall of Billy's bedroom, there is a Whitesnake poster. The band Whitesnake wasn't formed until 1978, 3 years after the film's setting.
(at around 46 mins) As George and Kathy drive away from the hospital and through town; contemporary vehicles can be seen at an intersection, even though the movie takes place in 1975.
The book Kathy reads at the library makes a few references to the Salem witch trials having happened in 1671, when the correct year is 1692-3.
There is a shot of the whole house from the outside and you can see a camera on its track run the whole length of the house.
After Jodie is pulled down from the roof and is being yelled at, there is a modern door-alarm sensor visible on the door.
When George and Kathy visit the house for the first time to see if they want to buy
the house and Kathy runs out of the car to greet the real estate agent, George tries to call her back to the car saying "Katherine." The real Kathy Lutz's name was Kathleen.