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)
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)
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.