Potassium chloride is notoriously difficult to dose accurately: the plasma concentration, usually between 3 and 5 mg/ml gets elevated 'artificially ' just by letting blood samples stand for several hours ; red blood cells contain about 135 mg/ml of KCl (potassium chloride) and they often degrade (explode) with time so the plasma concentration rises markedly.
The toxicology report is said to have found high levels of potassium chloride. Potassium chloride is a normal serum component and high levels of KCl would have been detected on routine chemical analysis. Toxicology testing would screen for drug levels if no cause of death was determined from routine blood chemistry.
Propofol is a milky liquid (aka "the Milk of Amnesia"), but the bottles of propofol show a clear liquid. It is an anesthetic used for short-term procedures: it inhibits your short term memory, so you do not remember any pain.
After Rose dies, Mariel comes into the operating room with no PPE at all, contaminating the room.
In the video watched at the police station, the vlogger's nose is slightly shiny. Probably to make the viewer concentrate more on her nose.
At approx 13 minutes, Sargeant Dodds says (of Al)"you declared her dead at twelve eighteen in the morning"- but he should have said "afternoon", as it was after 12 noon.
A young woman dies on the operating table, and within a couple of days the coroner accepts the surgeon's opinion, endorsed by his wife, that she had suffered a heart attack. He does not call for a post-mortem, and allows immediate cremation. Although it has been revealed that the coroner is in the wife's pocket, he could never expect that such a massive dereliction of duty would go by without ever coming to light.