And Here's To You, Mrs. Azrael - S3-E9
Factual error: They state that the heart monitor on "Nicole" never showed any movement at all as she was being smothered, because the killer swapped it out and put it on herself. When Mrs. Rollins was smothering her daughter thinking it was Nicole, her heart rate would have raced and her blood pressure would have gone up a little as she strained to hold the bag over her face. The monitor would have picked that up.
Chosen answer: Probably to broaden the scope of the show's plot and give the audience a chance to see the characters in a different setting, People act differently at home from the way they do at their workplace. By the ninth season, the characters would have become overly familiar and predictable. It gives the writers a chance to do something different with them.
raywest ★