These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Critical Dissonance: Despite being box office successes, the first 2 films have received mixed reviews from critics.
Designated Villain: Natalie in Home Alone 4. We're supposed to hate her just because she's rich, is dating the dad after he divorced the mom, and doesn't want her Christmas ruined.
Averted with the hotel concierge in "Home Alone 2". He is depicted as a bad guy from the get-go just for being suspicious of Kevin when, in fact, he and the rest of the hotel staff have every right to be wary of a ten-year-old checking into a four-star hotel by himself. So that's why the second film has him cross into actual bad guy territory by sneaking into Kevin's hotel room to spy on him while he showers, scaring him by threatening to call the police instead of kindly asking Kevin why the credit card is reported as stolen, and generally behaving as though he's eager to catch Kevin out of spite.
Hey, kids! Are there burglars in your house? Better try and fight them off then!
Do be sure to phone the police, but not until they've made it past all your traps that could have bought you enough time for the police to arrive.
The second movie seems to imply that being a parent makes it okay to forget the lessons they learn as well as to lecture their youngest son about being a pest, expecting them to learn about being respectful, while never even noticing that they themselves are part of the problem. It's no wonder Kevin acted the way he did, in both this movie and in the first one.
Also from Part 2: If you're marooned in a strange city, don't go to the police station! Go to an expensive hotel. And if you overhear some crooks planning a robbery, alert the cops by smashing the store window while the robbery is taking place to set off the alarm. To be fair, after that whole Christmas pageant fiasco, Kevin wasn't feeling too fond of his family at that point so, well, he wasn't thinking clearly. As for breaking the toy store window, he had to set off the alarm quickly to stop Harry and Marv from stealing all that charity money, and he did tape an apology note addressed to Mr. Duncan to the rock before throwing it.
Fanon Discontinuity: The fourth movie, universally agreed on there. The third film also gets this, though not as much as the fourth.
Germans Love David Hasselhoff: The first film is so popular in Poland that watching it has become a cultural tradition during Christmas. This is largely because due to it being one of the first Western films shown in the country and it being released at around the same time that Lech Walesa was elected President, the Polish population has come to associate it with the fall of Communist rule.
Genre Turning Point: This made family-oriented film-making a much more attractive proposition for studios, in tandem with the animation revival the previous year's The Little Mermaid inspired.
Hilarious in Hindsight: In the first movie, the family remarks on their tab for the pizza they ordered: ten pizzas, twelve bucks each... ironically in this day and age (taking price hikes and inflation into consideration), twelve bucks is essentially what you pay now for a delivery pizza (depending on the chain).
Ho Yay: Nothing graphic, but you might say that Harry and Marv bicker like an old married couple, and you might also note that (aside from the made for TV sequel, which ignores continuity in many ways, and removes Harry from the story) neither of the thieves mentions having a girlfriend or a wife (Harry wears a wedding ring, but this could be handwaved as his wife being dead or in jail, or as the ring being stolen). This would also explain why Harry puts up with Marv, since he is certainly not the brains of the operation and not much use for brawn either, being defeated by a child.
Harry is a hot-tempered burglar who tries to bite off Kevin's fingers in the first film and tries to shoot Kevin in Central Park in the second film but considering all the sadistic and nasty things Kevin does to him(and Marv), especially in the second film, few people wouldn't feel sorry for him.
The concierge in the second film, meanwhile, is a little overeager to bust Kevin for "credit-card fraud" and is an all-around smarmy jerk but watching him get outsmarted and humilated by Kevin, and later slapped in the face by Kevin's mother, makes him pitiable.
The criminals in the fifth movie, especially Sinclair who has a valid reason for wanting to steal the painting.
Just Here for Godzilla: Many of the people are watching the series mainly only because of the traps at the second half of the film.
Love to Hate: Harry and Marv. Yes, they're bad guys, but they completely steal the show.
Marv's girly scream was the basis for a popular YTMND fad. Sites with unsuspecting titles would reveal itself with Marv's spider scream turned up to speaker-shattering levels. The name of the fad? "AAAAAAAAAAAAAAAAAA"
The Game Grumps have played the SNES version of the game - which really isn't much better.
And on that note, JonTron made a video about the franchise's tendency to have this trope there.
Rescued from the Scrappy Heap: Buzz at the end of the second film, considering that he was the one to acknowledge the fact that it was because of Kevin that the McCallister family is able to have a hotel room full of wonderful Christmas presents and insists that Kevin opens the first one.
Surprisingly Improved Sequel: While it still wasn't on the same level as the first two films, the fifth Home Alone film is a noticable improvement over the fourth, actually feeling like a Home Alone film.
Tearjerker: After his encounter with "Santa," Kevin walks by a house and sees a family enjoying Christmas together, causing him to stare at them longingly. And all while "Somewhere In My Memory" plays in the background.
They Just Didn't Care: Or, more accurately, they cared about the wrong things. Since Home Alone 4 was meant to lead into a TV series, the focus was on setting that up rather than being a faithful sequel to the first two films. As a result, most of the subplots go nowhere (since the family has to get back together at the end), and Kevin and his siblings had to be cast with very young actors who could be kept for several seasons of the show.
Values Dissonance: The scene with the airport clerk in the first film. If you're a parent, you're likely to side with the mother worried over her son and having to deal with the incompetence of someone trying to follow procedure when there are important personal things at stake. In contrast, if you've ever worked with the public, Kevin's mother berating, interrupting, and screaming at the clerk who's only trying to do his job in an unusual and tense situation is uncomfortable to watch. Especially if you're an airline employee who has worked either at a check-in counter or as a gate attendant, and have dealt with this issue.
Wangst: Harry at times, especially in the second film.
In the sequel, Marv stealing many things in broad daylight, swiping coins from a sidewalk Santa's coin tray. He doesn't get caught, but considering he just broke out of prison, he might want to be a little more careful.
Harry does point this out, though Marv responds by giving the duo their new nickname; Harry does not look impressed.
In the first, after falling on the broken glass, he then walks on it instead of simply clearing the way.
Remember, Marv is the one that pushed for the "Wet Bandits" motif in the first movie. After being arrested, a cop jokingly thanks him for that, saying, "Now we know which houses you hit."