After the bat falls on the Burglar, there is an hourglass in the foreground with most of the sand in the top. In the next shot, all the sand is in the bottom.
When William enters the blue room for the first time, studio lights are clearly following him to illuminate the room as he's walking forward.
In "The Elemental" segment, during the exorcism, a yellowish dog figurine on the right side of the mantle gets knocked off. In a following shot it is back on the mantle and explodes.
In "The Elemental", when the man's wife is scratched by the elemental, there are claw marks on her shoulder, which have disappeared by the time they are in bed later.
When the cupboard door is first seen before being replaced, it is considerably more narrow. Later after the cursed door is removed and a standard door is replaced, it is much wider than the original.
In "The Door", it would appear that the sculpted head on the door moves from faces the inside of the house to facing the blue room in the final scene. However, upon close inspection, there's a sculpted head on each side of the door.
When Emily lights a black candle, the lighting is too strong to be coming just from her candle and it's obvious studio lights lighted the room.
In "Act of Kindness", the ex-service man's sign is misspelled. The R is missing.