Continuity mistake: The babysitter answers one of the early calls saying "Robert, I don't think this is very funny." The pencil and papers have completely changed position on the table. (00:07:30)
When a Stranger Calls (1979)
1 continuity mistake
Directed by: Fred Walton
Starring: Charles Durning, Carol Kane, Rutanya Alda
Continuity mistake: The babysitter answers one of the early calls saying "Robert, I don't think this is very funny." The pencil and papers have completely changed position on the table. (00:07:30)
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.
TedStixon