When Abbey the Demoness is in the netherlands in the hotel with Ben, in one scene she has her arm around his shoulder, in the next she's leaning back on that same arm with no time interval in between.
As Kristin is descending the stairs at home, her head bumps one of the stars suspended over the steps. If this were a common occurrence, as it should be since the stars have been there for quite some time, the bottom leg of the paper star would show some denting or crimping damage, or staining from frequent contact with hair.
When Kristin is trapped between floors in the elevator, her hand is alternately shown about a foot below the red STOP button, and with her fingers only a fraction of an inch away from being able to depress the STOP button. This view changes more than once.
The team refers to the symbol carved into the floor under the child's carpet as a pentagram, a symbol of devil worship. It's not. It is a pentacle, a symbol of Wiccan/Pagan mysticism. The former features a star connected at it's points by straight lines, whereas the latter features a star surrounded by a circle. Any experts in the occult would know this.