Blooper

Characters mention the titular Open House begins at 11:00 several times. The sigh outside the house says it starts at 10:00. When Naomi wakes up Logan later she says "we have to get out for the open house." He asks her the time and she responds "1:00."

When Logan and Naomi first meet their neighbor Martha in the store it is nighttime. Shortly thereafter they arrive at the mountain house in full daylight.

The son is exploring the basement and walks past the furnace room where the hallway veers right. In the next scene we see the hallway had just veered left.

On their first evening in the house, when Logan goes to check on her sleeping mother, the picture under her pillow changes position between shots.

Logan can't call 911 because the cell phones indicate the SIM card has been removed, but in reality you can always dial 911 even if the SIM card is missing.

The water in the shower becomes cold because the water heater has been turned off. The water heater is turned back on, and the shower has warm water again. That is not how a water heater works. It holds a full tank of hot water that can be used. Later, it will take a long while before another tank of water can be heated.

Water in the shower would not go suddenly cold if the water heater was off. It would get gradually colder as the hot water in the heater was forced out by the cold water.

In the beginning of the movie, Logan goes down into the basement to check the boiler. When he goes upstairs, he breaks a stair. Later in the movie, Naomi goes down to the boiler, but when she back upstairs, the stair is suddenly repaired. Later in the movie, the stair goes back to being broken.

Logan's foot falls through a broken step during his first trip up from the basement. Naomi steps in the same spot barefooted without issue when she climbs the steps after igniting the water heater.

At the beginning of the movie when the father is in the store getting eggs, he closes the cooler door and there are 3 rows of milk, each row having a different color lid, green, red and yellow. Indicating 3 different types of milk, like Vitamin D, 2% and skim milk. But at closer look, all the milks have the same 2% label on the front of them, they should all 3 have different labels to coincide with the different color lids.

When the hot water goes out the first time and she blames her son, he just lets her go to the basement instead of mentioning someone definitely moved his cereal bowl and someone is in the house.

At the beginning of the movie when the father is in the store getting eggs, he closes the cooler door and there are 3 rows of milk, each row having a different color lid, green, red and yellow. Indicating 3 different types of milk, like Vitamin D, 2% and skim milk. But at closer look, all the milks have the same 2% label on the front of them, they should all 3 have different labels to coincide with the different color lids. Then again when Logan and his mother are shopping at the Market when they first get to the mountain, Naomi get milk from the cooler and again the milks have red, light blue and dark blue lids, but all the labels are the same again for all the milks, which is 2% Milk.