Alternative Character Interpretation: Vera and Lombard's relationship in the 2015 BBC adaptation. Was there some genuine affection on either or both of their parts, or were they just manipulating each other's sympathies for their own ends? Was Lombard's pleading for Vera to trust his belief that the murderer was neither one of them sincere or was he just trying to save his own skin? Furthermore, was Vera's proposal to Wargrave to frame Lombard for the murders simply the desperate plea of a woman searching for any way to persuade Wargrave not to kill her or the conniving words of a Manipulative Bitch who had never truly loved Lombard?
The Harry Alan Towers film adaptations are full of such moments. For example, in the 1965 movie, Lombard and the butler get into a random fistfight that lasts about one minute before the judge says "Now, now, that's enough"... and it is. It is promptly forgotten, and never brought up again.
Or the 1989 movie. There are several moments that fit this trope, but one that stands out in particular is the usual "Marston plays the full rhyme on the piano" scene that is usually in each adaptation (and ends up being crucial to introducing the rhyme to the audience)...except instead of actually playing the rhyme, Marston plays a few seconds of "Mad Dogs and Englishmen". Why? No one knows. And no one spends their time speculating on it, either.
Hate Dumb: Those who criticize the anti-Semitic lines in the book and in the BBC adaptation often fail to realize that such lines are said by characters (Lombard in one case, Emily Brent in the other) that we are clearly not meant to sympathize with.
Hilarious in Hindsight: A General MacArthur, written before World War II. As such, when the book was adapted into a play in 1943, MacArthur's name was changed to McKenzie.
It Was His Sled: All the guests are responsible for the deaths of someone while managing to escape the justice, Judge Wargrave is the killer and everyone is dead at the end of the novel. It's safe to say that someone who didn't already read the book should finish it before browsing its tropes. Of course, given that this is one of Christie's most famous books, this isn't surprising.
Lost in Imitation: Nearly all English-language film adaptations of this book have the 1945 film's fingerprints all over them, from Anthony Marston playing the nursery rhyme on a piano to Vera and Lombard's romance to Vera's shooting of Lombard turning out to be faked and Wargrave taking poison instead of shooting himself like he does in the book.
Misaimed Fandom: Let's just say that if the internet had existed when the book was first published, or if Agatha Christie had lived long enough to see the internet, she would have done a lot of head-desking at the discovery of how fans found some of her most intentionally despicable murderers to be sympathetic.
Christie was fond of having a sympathetic character turn out to be a murderer, because these types of characters tend not to be suspected by the reader. However, the notion that fans would still find these characters sympathetic after their guilt had become clear beyond a doubt would certainly make her mind boggle.
Mis-blamed: Rene Clair, director of the 1945 film version, received a lot of criticism for changing the ending of the book. A lot of people did not realize that the basic idea for the film's ending came from Christie herself, having changed it upon adapting the novel for the stage in 1943; Rene Clair simply brought about the Revised Ending in a different (and more convoluted) way.
Vera Claythorne's internal monologues in the book seem like this to some.
Anthony Marston's demise in the game.
A lot of the game can be incredibly narmy, mostly because of the cheap, limited animation and sometimes very poor voice acting.
Rogers' reaction to the death of his wife in the 1989 film. And his own death.
Blore's death in the 2015 miniseries. Instead of being bashed over the head by a marble clock shaped like a bear, Blore is stabbed to death with a carving knife while the killer apparently wears a polar bear rug like a poncho! Regardless of whether the killer could actually see out the open mouth, without the blurry-edged screen that implies that Blore thinks he's hallucinating it would look utterly ridiculous, instead of WTF?
Not His Sled: Nearly all adaptations completely change the book's ending to the point where the 2015 BBC adaptation actually following through with the original ending feels like a Meta Twist. The video game adaptation goes one step further and changes the identity of the killer, retaining Wargrave's faked death plan to make it appear that he's still the killer to players familiar with the book until he turns up 100% dead later on.
Paranoia Fuel: in the 2015 adaptation, Lombard's flashback to his crime shows he wasn't alone when he did it; he was the leader of a four or five man team. Lombard even Lampshades this as to how the story got to U N Owen, saying 'it's amazing how people have an attack of conscience once they're home safe' (approx). What happened to the other men who participated?
Romantic Plot Tumor: Averted in the original novel, and to a certain degree in Agatha Christie's stage version and the 1945 movie as well, but the Harry Alan Towers adaptations put much more focus on the romantic subplot between Vera and Lombard than on the actual mystery itself.
What an Idiot: The reason why Vera murders Cyril in the original novel and the BBC adaptation: her lover Hugo would have inherited a wealthy estate if not for Cyril being born. Hugo keeps emphasizing, however, that he loves his nephew and dotes on him. Vera gets a spur-of-the-moment idea to allow Cyril to swim in the ocean, when he's too young and lacks the stamina, so that Hugo can inherit the estate and marry her. Unsurprisingly, Hugo ends their relationship and vanishes after the coroner deems Vera innocent, Drowning My Sorrows because he never wanted Cyril to die.
Many, many fans find MacArthur to be the most sympathetic of all the guests. He was pretty much dead before he came to the island.
Armstrong committed a terrible accident that caused his patient's death, which not only haunted him and brought him to an island to be killed, he ends up becoming the killer's fearful pawn. Toby Stephens plays his woobie status Up to Eleven in the 2015 adaptation.
Likewise, Ethel Rogers was pretty much pressured into murdering her former employer by her domineering husband, and had to live with the guilt until she was ultimately murdered for the crime she didn't want to commit. This was why the killer chose to give her a relatively painless death.
Beatrice Taylor was fired by Emily Brent after getting pregnant and commited suicide after even her family had rejected her.
Whether by Vera or (in some adaptations) not, poor young Cyril was betrayed to his death by someone he loved and trusted.
In the original, Hugo Hamilton as well. Wargrave coaxes the story of Cyril's death while the latter is Drowning My Sorrows on a boat. Hugo is completely shocked about what Vera did for him, and regretful that his refusal to marry her encouraged her to murder his nephew.
WTH, Costuming Department?: The game has Vera dressed in a bright fuscia sleeveless dress which would have looked pretty scandalous in 1939, especially for a would be secretary/former governess. It doesn't help that her outfit is very bright compared to the subdued color schemes of the other characters, and a large portion of the game rooms.