Question: Who did the demonic voice that told the priest blessing the house to get out?
Question: When it is mentioned that Ilia is Deltan, a couple of the male Enterprise crew members (Sulu in particular) look very interested when they hear that. Why? Also, why was it necessary for her to say that she has taken an oath of celibacy?
Answer: Deltans exude an intensely potent and effective chemical substance known as pheromones, which act as signals arousing an intense sexual reaction in other species (in other ST material it's inferred that its potency is so extreme that a non-Deltan risks insanity in a sexual encounter with a Deltan). Upon entering Starfleet, Deltans must swear "an oath of celibacy" so as not to influence or take advantage of crewmembers. That is why Lt. Ilia stated that her "oath of celibacy" was on record.
Question: How was the underwater shark attack scene done? Things I want to know are : How come the shark didn't attack the actor? And how did all the make up stay on the actor UNDERWATER? Does anyone (also) know how long filming this scene took?
Chosen answer: After the original zombie extra fell ill, the shark handler was made up to play the underwater zombie. The shark was tame, or at least enough to not attack the handler. The makeup would have been latex/oil based, so it would not have been affected by the water. I remember from the commentary that the filming took 1 or 2 days.
Question: At the beginning, Jill tells the police that she believes the caller is watching her through the windows. Since he calls her, how is this possible since cell phones did not exist at the time this movie came out?
Answer: Sorry, editing my answer because I misunderstood the question. The caller is using a different phone line in the same house. It's possible to have multiple different landlines/phone-numbers in the same building. However, Jill doesn't realise this and probably assumes he's watching her from a different house using binoculars or something similar.
Answer: George Lutz.
How was it accomplished?