Factual error: No gearbox problem would cause the noises in the episode, it was a clutch problem.
Character mistake: When Angus is found dead, he left a word, "murder", in steam on the mirror. Daisy cleaned off the word before anybody, except Laura, could see it. Later, Daisy said that Laura was annoyed with her because she had wiped the words, plural, off the mirror. But it was only one word.
Factual error: Bert is using an oxygen-acetylene torch, not butane, and the stop valve is NOT the large T piece on the regulator. Butane cannot cause a heart attack.
Continuity mistake: When Angus is found dead, Daisy has her hands steepled in front of her face, but, in the next shot, her hands are lowered to her chin - except in the mirror, where they are still steepled in front of her face.
Character mistake: When Rosemary is told that the hotel the girls are staying in used to be used for movie locations until it was restored, she says that the names on the rooms are film titles and Ben, the brother of the man who runs the hotel, agrees with her. Problem is: the girls' room is called Ebenezer Scrooge, but he is a character from the book "A Christmas Carol." And Lorna Doone, another room, is a character from the self-titled book written in 1869. It was eventually made into 2 TV movies in 1990 and 2000. It's more likely the rooms are named after very much classic characters, because the hotel was used for old movies.
Continuity mistake: At the beginning, Rosemary has her glasses in her hand and she tries a couple of times to get her glasses case out of her bag, but she doesn't succeed - except, suddenly, her glasses are gone.
Plot hole: Dan, the policeman, finds a love letter written by Ben to Daisy, Dan's sister. The letter says "Meet me in the summer house tonight." When the girls arrived 2 to 3 days ago, Ben and his brother were arguing about the letter, which was written on blue paper. When Daisy is killed, Dan, ridiculously, accuses Ben - only on the blue letter as evidence, which we know was written days ago, and Daisy was killed in the afternoon, not at night as the letter says; plus, Dan says Daisy was struck with a heating tube, just like the ones where Ben works on the winery, but anyone could have picked it up. The evidence is stupid, but Ben is arrested, placed in handcuffs and taken away.
Revealing mistake: Near the end, where Rosemary is driving the tractor and delivering wet steam to kill the weeds, you can see the vines moving as the camera brushes them aside as it closes in on Rosemary.
Continuity mistake: The first time Laura attempts to enter the Ebenezer Scrooge room she can't fit and Rosemary has to give her a couple of hard shoves from behind. But, later, she goes in and out easily.
Continuity mistake: When the girls are standing in the doorway of Anges's room, considering staying there, in the reflection of the mirror, Rosemary's hand is over her mouth, but, in the next shot, not in the mirror, her hand is over her forehead.
Continuity mistake: At the very end, the girls, Ben and Burt are celebrating with champagne, but Laura's glass isn't as full as it was in the previous shot and, if you look closely, you can see that she only pretends to take a sip.
Plot hole: When Daisy is killed, Dan comes around to collect her things. So we'll be able to see him reading one of Daisy's love letters from Ben and accuse Ben of Daisy's murder, when Dan takes the box from Stuart, who is holding it with his hands underneath, keeping everything in, he holds the box with his hands on the side, deliberately, so the love letters fall out to the ground - and how convenient that nothing else falls out, just the love letters. But the letters were written before the girls arrived - they saw them - so how could Dan accuse Ben when the blue one has Ben asking Daisy to meet him in the summer house, but it was days ago, not relevant now.
Plot hole: When Laura, alone in the girls' room, hears the noises in the attic, she runs to get Rosemary. Problem is: Horace is the one who makes the noises and when Laura finds Rosemary, Horace is in the bar - not downstairs, making noises as he should be.
Answer: Regents park.