Continuity mistake: When Victor Buono circles the ad Jane placed in the paper, the only way to contact her listed in the ad is a phone number. However, when his mother calls acting as his secretary to schedule him an appointment for 4:00, no one gives or asks for an appointment.
Suggested correction: Jane's address is never given in the call, but Buono shows up at the house looking at a paper to find her location. The time of 4 o'clock is established in the call. (Just watched the scene again to be sure).
The address is not given in the call or is it printed in the paper. How did Flagg know where Jane lived?
White pages of the phone book.