Afterbirth - S1-E12
Continuity mistake: When Stacy and Miguel (the new owners of the house), are making out in the kitchen, her shirt goes from off her shoulders to back on her shoulders across several shots.
Afterbirth - S1-E12
Continuity mistake: When Vivien and the maid are sitting in the kitchen, one shot shows the maid from the side with her hands in front of her on the table. The shot changes and instantly her hands are holding a coffee mug in front of her lips.
Piggy Piggy - S1-E6
Continuity mistake: The people that Tate murders at school have different wound patterns. Episode 5 they say what Tate did to them, episode 6 shows the attack. Episode 5 the goth girl says Tate asked her if she believed in God before shooting her - episode 6 he asked her nothing, instead just shot her. Episode 5, the guy in the letterman jacket illustrates his wound to be a single round to the head - episode 6 he shoots the letterman with a shotgun in the chest, not a handgun to the head. Episode 5 the cheerleader shows no apparent wounds of being shot - episode 6 Tate shoots her in the face with a shotgun.
Chosen answer: Because on Halloween, the souls of The Dead are said to roam the Earth. That includes those souls that are trapped within the walls of the "Murder House".
THGhost