A two-fold one for the "Nightmare Tunnel" sequence:
Slugworth's appearance. The first time you see that scene, it gives the impression that the tunnel is supposed to be some kind of mind probe that shows people their greatest fears, so we assume that Charlie sees Slugworth because he was being "haunted" by the offer that he gave him. But then we learn that "Slugworth" was actually an employee of Wonka's all along... so it makes perfect sense that Wonka would be able to project his image on the tunnel.
Consider the fact that "Slugworth" works for Wonka, and that his offer of cash was really a Secret Test of Character that all five children got. Bribing kids with cash and sending a creepy dark-suited man to ambush them in dark alleys would be a good way to intimidate them into committing a crime, but so would scaring the bejeezus out of them by showing them an image of the same man in a dark tunnel filled with images of their greatest fears. Charlie proved himself worthy of inheriting the factory by proving that, not only could he not be bribed into ignoring his conscience, he also couldn't be scared into ignoring his conscience. Considering the future of Wonka's entire factory rested on that one tour, it makes sense that he would want to test the children's resolve at every opportunity.
Slugworth seems to approach every child who wins a Golden Ticket just as they acquire it. Notably, we never see him come to the lucky winner of the last Golden Ticket in Paraguay. Whether this was intended or not, it seems to aptly foreshadow that the last Golden Ticket it still out there somewhere.
Slugworth offers riches for a contestant to steal an Everlasting Gobstopper. However, earlier in the film, it was established that no one entered or left the factory for three years. There's no way Slugworth would have even conceived of such a prototype unless he was under the employ of Willy Wonka himself.
Presumably Wonka has some means of arranging for candy distribution to retailers and being reimbursed for orders, most likely by mail. He's not giving away candy, after all, he's selling it. So Slugworth could have been informed by a retailer that Wonka had sent out discreet preliminary queries about how large of an Everlasting Gobstopper order the seller would be willing to purchase per month. He wasn't, but it's something that could have happened.
Note that it's also telling that Slugworth doesn't just offer to buy the ticket itself off of Charlie on the spot, or even show up with a couple of paid goons and mug the kid for it. Had Slugworth turned up on Wonka's doorstep with a legitimate Golden Ticket, what could Wonka have done? His own contest terms stipulated that the Ticket-holders had every right to a tour.
There's no way the half dozen or so rooms we saw were the whole factory. If Wonka heard that someone he felt unsafe revealing his secrets to had won a ticket, he could have restricted the tour to more mundane areas where, even if the person swiped something, the consequences would be minimal. For that reason, had it really been Slugworth, bribing the kids for a later payout would be a safer idea, as odds would be higher they'd get access to things Wonka wouldn't dream of letting Slugworth touch with a 50 foot pole. Plus, if he had bought the ticket off of Charlie or mugged him for it, considering the coverage of this contest, that would probably come back to haunt him from a business standpoint; if a winner reports that the ticket was taken from them one way or another, and a competitor shows up at the door on tour day, it wouldn't be hard for people to connect the dots and they'd likely respond by boycotting him.
Related, it's implied that Slugworth approached every one of the contest winners with that offer, though the audience only saw him approaching Charlie. Given that these children came from across the United States, Germany, and the United Kingdom, it's easy to tell how he would know where they are and who they were (since they were all broadcast on television), but one other way he would have known was he works for Wonka - he would easily know which box contained the golden ticket shipment and where it would go - even down to the specific candy shop or supermarket.
We see him approaching Veruca as well. Charlie and Veruca are the only two who we actually see in the immediate aftermath of finding the ticket; the others we only see in the TV broadcasts until the day they arrive at the factory.
Rewatch the movie, we see him approach all of the winners. He is a waiter putting food on Augustus' plate while he talks to him, a reporter with a microphone with Mike (the one who keeps going back and forth between Mike's mouth and other people around them), and as the camera pans away from Violet's father and his spiel, we see him whispering in her ear. The movie was very deliberate about showing us how he was there at every ticket acquisition and spoke with every child.
The previous troper is saying that for Augustus, Violet, and Mike, Wilkinson first appeared inside the gaggle of reporters after the ticket finding had already been made news. With Charlie and Veruca, he was there exactly when it was found.
Wonka's nonchalance at the bratty kids' personal safety and their parents' concern for them (along with placing priority on the sanitation of his factory over their lives and the emotionlessness of his pleas for the kids to keep out of danger) makes sense if you buy into the Secret Test of Character aspect of the factory tour and the idea that Wonka knew the other kids would inevitably give in to their greed and selfishness and disobey him, and the barely-veiled contempt he has for them or their parents, Charlie and Grandpa Joe. He is gracious enough to save their lives, but has little concern for them otherwise, and is whittling them down to find his worthy heir. The only ones he genuinely cares for and disappointed over are Charlie and Grandpa Joe post-Fizzy Lifting Drinks incident.
It's just as likely he's simply aware that the children are in no real danger of loss of life or limb.
Each of the kids who "drop out" of the tour wear clothes that correspond to their "fates." Augustus Gloop is dressed in dark brown (falls into a chocolate river and is sent via pipe to the Fudge Room). Violet Beauregarde is wearing blue (turned into a blueberry). Veruca Salt is dressed in red (dropped into the furnace). And Mike Teavee is dressed up as a cowboy—like the ones on TV.
Wonka's entrance. At first it appears to be a mere "Oh, look at how silly Wonka is!" moment, but as Gene Wilder (who came up with the idea) stated to the director, it is a clue that you can't trust Wonka. He will lie, he will present himself in a false light... you have no idea who he truly is, so you better be careful.
If you're somewhat experienced in minor SFX, you know that real glass typically isn't broken in movies, because glass is not soft. What is movie glass made of instead? Sugar. What does the Glass Elevator break through in the final scene?
In the "Pure Imagination" song, the kids and their accompanying adults are shown to be gorging themselves on candy. Meaning that Willy Wonka was giving them no excuse whatsoever: they were given a chance to satisfy themselves entirely without a hint beyond the word of Slugworth of what might be further inside, so any further interference with Wonka operations could only be the result of a Fatal Flaw, whether an immoderate desire to consume everything, unbridled narcissism, or just the plain old greed to accept Slugworth's offer. As Mr. Wonka was looking for a successor, any child who broke the rules further in had to be more than merely hungry, or even all that curious: they had to be either willing to betray the offer of a lifetime for sheer money, meaning they were already likely greedy enough to fire or abuse the Oompa-Loompas or otherwise cut costs in the factory in a way detrimental to Mr. Wonka's ideals, or they had to be so twisted that their desires would run Wonka's factory right into the ground. Thus making the Secret Test of Character more revealing.
At first glance, Wonka's instructions for the Chocolate Room make no sense. First, he lets the kids eat anything they want. Then, he warns Augustus against drinking the chocolate river. Why let them eat everything in the room except one thing? That's like telling people they can eat the fruit from every tree in a garden except one. Wait a minute...
He specifically tells Gloop not to eat from the river because, unlike the rest of the food in the room, the river is leading somewhere else, thus Gloop was contaminating someone else's food with his dirty hands.
Augustus's Oompa-Loompa song. It’s true that Wonka relies on people to eat a lot of the chocolate. If people eat too much of it in too short a time, they’ll get health problems later on, meaning they’ll have to limit or stop completely (e.g., obesity forcing them to limit or eliminate their intake while they change their diet and lose weight). All things in moderation. This does not, however, change it being strange hearing this lesson from workers at a chocolate factory that makes products mainly for children.
It also brings on a bit of Fridge Hypocrisy, as his contest has led to innumerable bars being purchased and eaten, with greed and gluttony driving it.
How did Grandpa Joe obtain that Wonka bar? After the fake fifth ticket is found, the candy store owner tells Charlie he was hiding the bars he was selling. With Wonka bars so hard to come by at the time, it's likely that he saved it so he could sell it to Joe.
Joe also could have had the newsstand owner Mr. Jopeck do it for him. They apparently go way back, judging by Mr. Jopeck telling Charlie "Say hello to your Grandpa Joe" earlier in the film.
Or given the tobacco money to Charlie's mother to get an extra present just from him, as he seems to be Charlie's favorite grandparent.
Mr. Slugworth offers to pay each child a large amount of money if the child will obtain an Everlasting Gobstopper during the tour of Wonka's factory. During the film, Wonka gives each child an Everlasting Gobstopper but makes them promise to keep it to themselves. At the end of the movie, it's revealed that the man isn't the real Slugworth and actually works for Wonka. The whole set-up is a Secret Test of each child to see if they'll keep their promise to Wonka. The truly clever part of this is that Wonka has created the situation in such a way as to reduce the chance of an Everlasting Gobstopper going to one of his real competitors. If the child keeps the Everlasting Gobstopper, there's no problem. If the child sells the Everlasting Gobstopper to "Mr. Slugworth", Wonka gets it back.
The only way there could be a problem is if the child and/or their parent go to another of Wonka's competitors and ask how much they'll pay for an Everlasting Gobstopper. If it's more than "Slugworth" promised them, they could sell it to the competitor and Willy Wonka is in big trouble.
Further Fridge Brilliance: the "Everlasting Gobstoppers" are almost certainly nothing of the kind. They're just bait for the trap. Wonka's not fool enough to let four disgruntled brats walk away with an actual genuine prototype of an industry-shaking development. Assuming any of the rejected children make it to one of Wonka's other competitors with their gobstopper, the odds are practically 100% that they'll just turn out to be ordinary candy.
Even further Fridge Brilliance than that, Wonka's real competitors likely wouldn't even be interested in the Everlasting Gobstopper, given that the selling point is that people can buy drastically fewer of them than any other candy, considering they never lose flavor or get smaller. Wonka's competitors are interested in his unique recipes, but only to the extent that they can use them to make more money. The Gobstopper is certainly not a good long-term investment for people only in the candy business for the money.
At the end of the film, Charlie's grandfather asks when Charlie will get his lifetime supply of chocolate, and Wonka replies that he doesn't get it, because he's broken the rules. Charlie apparently apologises by returning the Everlasting Gobstopper to Wonka. But what has that got to do with it? (After all, Charlie hanging on to the gobstopper himself would be no guarantee that he planned to give it to Slugworth.) Charlie realized what his grandfather didn't: the Everlasting Gobstopper by itself is a lifetime supply of chocolate. He's accepting Wonka's judgment by giving it back, since after all, he did break the rules - thus showing that he understands Wonka's Weird Science and that even though he's acting like an ass, Wonka has a factory to run and has a point. Both excellent qualifications for what Wonka is looking for.
Charlie's teacher is depicted as an incompetent jerk. One subtle example of this is when he's teaching the kids about percentages and uses Wonka bars as an example. When Charlie mentions that he bought only two bars, the teacher says that he can't work with only two. This is particularly ridiculous because many chocolate bars are made to be broken down into smaller pieces; for example, fifty percent of a bar divided into ten squares would be five squares.
For those with a curious tooth, the percentage of 2 in 1000 would be 0.2%.
Also, yes, 10% half over again is 15%, but you hear the teacher claim that 20% is 15% half over again. Nope. 15% half over again would be 22.5%. 20% is 15% a third over again.
A small but obscure moment of Fridge Brilliance: In "Now!", Veruca seems to jump from wanting a golden goose to wanting a bean-feast. In fact, the centerpiece of a traditional British bean-feast is a goose, and the feast was once known as a bean-goose feast after the type of goose frequently served. Presumably Veruca wants a bean-feast to show off her fancy golden goose, rather than to consume it.
In the movie, at least, Wonka is shown putting shoes and other clothing into his recipes. While this is played for laughs, think about it: he's planning on selling the candy this stuff is made out of to children. These are inedible objects he's putting into candy. The parents were right saying that the health department would be all over him for this kind of thing.
This presumes that he was putting them into actual cooking machines and not simply messing with everyone.
What about the exploding candy? The recoil knocks Mike back and makes him fall over a shelf and the overall force apparently damages his teeth (we don't see it, but his mom cries out "Your teeth!" when she's examining him after the fact) and yet Wonka claims it's too weak.
This probably belongs under the Fridge Logic section with the part talking about how the limp-to-somersault intro makes you not able to believe anything Wonka says.
On a meta level, this film's Willy Wonka has developed huge use for memes. But the brutal irony here being that a lot of what Wonka and the Oompa-Loompa songs in all versions have against Mike Teevee are also very true of the meme culture. Where Mike's obsession with TV and not exploring more through reading easily translates to people being lazy on the internet instead of using it to learn and discover. A lot of these memes become a lot less funny when you realize the character in them probably wouldn't care much at all if most of the people making them suffered some Disproportionate Retribution more so than agree with you.
Veruca tends to get everything she wishes for. Most little kids tend to wish for a bunny, a puppy, a kitten, or, especially in the case of girls, a pony. Veruca obviously couldn't and wouldn't take care of them, and it's fairly doubtful her parents would know how, either. Did the pets all end up in a shelter? Even if they hired someone to feed them, would they get all they need (e.g. company for a rabbit and horse, since Veruca would most likely want it to be near her and not in a stable a while away; affection for all; training for a pony; etc.)? Most likely case is what happens way too often anyway - Kid wants a pet, loses interest after a few weeks, especially since a puppy or foal is not pre-trained and thus doesn't behave like the kid wants it to, and the poor thing ends up in a shelter.
At least there's hope that Mr. Salt bought her "only the best" pets, i.e. the most high-end, attractive, exotic, and desirable breeds available. That'd give them a very good chance of finding decent second homes.
Though the "Candyman" song seems cheerful and innocent, when learning about a certain serial kidnapper, pedophile and murderer called Dean "Candyman" Corll, it doesn't seem all that innocent anymore. Considering how flippant Wonka is about the children's safety it gets even worse.
Film Theory has made a pretty good case not only discussing how Wonka's factory has No OSHA Compliance (the fates of the children are just the start), but that Wonka could very well know this—the movie was made and presumably takes place in the same year that OSHA was established.
When Mike Teavee asks his dad when he’ll replace his toy gun with a Colt 45, he says he’ll get one on his 12th birthday. Considering he’ll act the same way he does while being interviewed by that time, he could kill his family and maybe even himself.
When Violet went into the juicer...where did the juice come out?
Immediately after filming the blueberry scene, Denise Nickerson flew home. Two days later, she was sitting in math class when suddenly her skin started turning blue, in front of her classmates. The makeup had seeped deep into her pores and resurfaced. This continued for weeks, with Denise being extremely concerned as to whether it would be permanent. Considering what this scene did for some people we'll just assume the juice left through Violet's pores, too.
not only discussing how Wonka's factory has No OSHA Compliance (the fates of the children are just the start), but that Wonka could very well know this—the movie was made and presumably takes place in the same year that OSHA was established.