Revealing mistake: When Elsa is waiting in the lobby, she's wearing a dress which shows her normal, not wooden legs. It's very apparent when she is crying on the floor.
Revealing mistake: When Tristan Duffy is sitting on the chair and looking through guys on a dating website to lure to the hotel, you can see he is just looking at photos in the gallery on the iPhone he's using. (has all the gallery interfacing) yet he clicks the screen and it makes a noise like he was on an actual dating app. (01:07:54)
Revealing mistake: As Iris is telling Detective Lowe about Mr. March when he built the hotel (with the flashback) in the close up shot of the police officer holding the handkerchief, you can see The Dead victim's stomach moving as the actor is breathing, although he's supposed to be dead. (01:01:35)
Blood Bath - S4-E8
Revealing mistake: Elsa's legs are supposed to be wooden prosthetics, but when she walks away from Ethel, who's holding a gun at her, it cuts to a shot of Jessica's calves which bend slightly as she walks. (00:00:14)
Camp Redwood - S9-E1
Revealing mistake: When Brooke parks her car, set lights are reflected in the driver's side door when she opens it to exit the vehicle.
Revealing mistake: When Dandy shoots Penny through the sheet, the second sheet flies out as it's hit with blood. But the sheet he shot through has no hole in it.
Revealing mistake: After Meadow tells Ali about the cult, Ali's phone shows that her phone call to Ivy has been active for 13 seconds, when in reality the call has been active for much longer than that.
Revealing mistake: After Hannah draws vials from the suspected bespeckled killer, he rushes through the hospital ward with no visible markings or needle pricks on his arm.
Answer: Moira's ghost form is unique because of the way she was treated when she was alive. To people who do not sexualize her and truly understand and view her for who she really (namely women), she is seen as an older woman. To people who objectify and don't care to see the truth (namely men), they see the young seductive Moria. It's a strong directorial choice to eventually show how Ben Harmen comes to terms with the truth of the house and himself.