The story is set in Windermere, compared to the original where it was set in Market Basing.
Instead of Hastings adopting Bob the dog, he's instead adopted by the Tripps after Poirot tells them that their old dog Albert gave his blessing.
Adaptational Early Appearance: Since Poirot is around before Emily is murdered, he's the one who suggests to her to change her will in order to throw off who might want to kill her, rather than it having happened before Poirot even starts his investigation.
Adaptational Friendship: In the novel, Hastings and Charles only become acquainted during the events of said book. In this episode, they're shown as old friends instead.
Adaptational Name Change: Jacob and Bella's children are named Alexis and Katya in this story, reflecting their father's Greek heritage.
Adaptational Nice Guy: Charles Arundell isn't the Black Sheep of the family here, and though he has his disagreements with his Aunt Emily regarding funding for his racing interest he's generally on better terms with everyone.
Dr Grainger losing his sense of smell which causes him to miss out on the signs of phosphorus poisoning is excised from this adaptation.
Mr Donaldson, Theresa's fiance and Miss Peabody, two characters from the book, are not in this adaptation.
Busman's Holiday: A straighter example than the book it adapts. Here, Poirot and Hastings make a trip to Windermere to witness Hastings' friend Charles Arundell attempt to break the water speed record, then end up getting involved in a series of events that culminates in two murders.
Death by Adaptation: Dr John Grainger dies after suffocating from carbon monoxide poisoning due to knowing about the phosphorus that killed Emily Arundell.
Embarrassing Nickname: Charles calls Hastings "Battler" (i.e. as in Battle of Hastings). A sheepish Hastings has to explain to Poirot the origin of the nickname.
"Eureka!" Moment: Poirot seeing Bob look at his own reflection on Charles' boat provides him with the final piece of the puzzle to solve the case.
He Knows Too Much: The murderer kills Dr Grainger because he found out about the phosphorus, and he just so happens to tell said murderer about it.
Karma Houdini Warranty: Unlike in the original story, where Bella Tanios manages to commit suicide after Poirot identifies her as the murderer, her culpability is made public and she confesses to the crime before being arrested.
Jacob Tanios is a Jerkass with a Hair-Trigger Temper, but he's ultimately found innocent and the medicine he gave to Emily, which was hinted at to be the cause of her death, turns out to be harmless.
Poirot spots a picture of the Tripps rowing a boat, which implies they were the duo that attempted to break into the Arundell home. Of course, it's the other pair of siblings, Charles and Theresa, who were said duo.
Spanner in the Works: The portrait of General Arundell falling from its resting place causes Charles and Theresa to panic while attempting to steal Emily's will, as well as for Wilhelmina to see them fleeing from the scene.
