Factual error: During the examination of the crime scene at the beginning of the episode, not one of the Crime Scene Officers or any of the police on site wear latex gloves. The supervising police officer picks up a vital piece of evidence - a small bag of jewellery - with bare hands! They have hopelessly contaminated the scene.
Plot hole: In the end, we see that Francesca entered the bedroom, ruffed up the bed, and tied herself up before shooting Shale. However, if Katrina hadn't entered the bedroom moments after the fatal shooting, where is Francesca's alibi? If Katrina weren't there, Francesca would have been sat there for possibly hours. The police would reasonably guess she shot him and then tied herself up. How did Francesca know that Katrina was going to be there and at what time in order to testify to her innocence? (00:41:00)
Chosen answer: It was a bottle of turpentine.
Methylated spirit, always coloured purple.