The original draft of the book was much more violent, with children being burned to death FROM THE INSIDE OUT, ground to powder while screaming in agony, drowning, cut to ribbons, crushed, etc. In fact, Violet seemed to be the only survivor along with Charlie.
The possible fates of the naughty children and Wonka's cavalier attitude towards them (e.g. when Veruca falls down the garbage chute, he glibly points out that the incinerator is only turned on every other day). Rule of Funny allows these to be Amusing Injuries rather than horrific accidents and the children ultimately end up (mostly) unharmed, however, the whole situation seems to be rather macabre.
Especially frightening if you're claustrophobic, and don't know that the kids survive their punishments. This makes Augustus Gloop's and Veruca's demises way scarier.
Veruca's scene is particularly nightmare-inducing if one thinks the scene over. She is forcibly held down (by squirrels), for quite some time, touched on shoulder and face while helpless, has her head patted to determine whether she is "good" (possibly with the knowledge that if yes, the squirels will attempt to crack her head), and then thrown down the chute. Does This Remind You of Anything? Little wonder that both the 1971 film and most stage adaptations make Veruca simply step on the chute door instead. This is the only demise with such aggressive subtext.
Oh, look, Mr. Wonka has a boat for everyone to ride on! What kind of whimsical shenanigans will they get into now? Oh look, a tunnel! Hey... it's pretty dark in here. What's going on, this is kind of weirdOHMYGODGIANTBUGSANDCHICKENSGETTINGTHEIRHEADSCUTOFFANDSLUGWORTHANDCREEPYSINGING
Wonka: There's no earthly way of knowing, which direction we are going, there's no knowing where we're rowing, or which way the river's flowing... is it raining, is it snowing, is a hurricane a-blowing? GASP! Not a speck of light is showing, so the danger must be growing; are the fires of hell a-glowing; is the grisly reaper mowing? YES! THE DANGER MUST BE GROWING FOR THE ROWERS KEEP ON ROWING, AND THEY'RE CERTAINLY NOT SHOWING ANY SIGN THAT THEY ARE SLOWING! WAAAAAAAAAAAAAAAAAAAA!!!!!!!
Not just for the viewers; apparently the other actors were told that they would be on a boat, and that Gene would do something, after which they had their lines. And that's all they were told. When everything goes shit crazy and people don't seem to be able to even speak right, it's because they CAN'T.
Wonka's unconcerned attitude toward the horrible demises of his guests are certainly unnerving, along with his general Nightmare Fetishist behavior. Memorable quotes include:
Probably the worst one, however, is the fan at the top of the Fizzy Lifting Drinks room. The fan makes the room impractical for a testing room, given the large possibility of horrific death if the tester fails to burp or the burping is ineffective. Therefore, the only good reason (to Wonka) to have it there is to kill anyone who has a taste. The scene itself is very horrifying, even despite the attempt by the filmmakers to use burping as Nightmare Retardant.
Charlie: HELP! We're gonna get killed!
The way Wonka grabs Veruca's tongue in the snozzberry scene is quite unsettling.
Wonka: We are the music makers, and we are the dreamers of dreams.
The opening sequence of the factory's production line is oddly eerie, and the music downright sinister. The film is darker than the 1971 version, but it isn't a damn horror flick!
Johnny Depp's portrayal of Wonka as a reclusive, downright creepy Mad Scientist.
Depp says it was partially inspired by the eccentric, unsettling nature of many a children's TV presenter; he wondered what it would be like if someone had those mannerisms all the time.
The puppets burning before the kids enter the factory.
The fact that Wonka was very calm about all the other kid's trials, EXCEPT VIOLET'S. The fact that Willy Wonka was running and hiding for cover made it horrifying (plus all the build-up and new graphics that made it look insanely real), he even begged for Violet to stop chewing the gum- "Hah hah, yeah! Spit it out."
Also, Violet's blueberry transformation was even bigger and more frightening. And the Mike Teevee musical sequence (Shout-Out to Queen's Bohemian Rhapsody).
The images of the house, Willy Wonka's flashback to his childhood, and the scene where the puppets in front of the factory suffer a Sugar Apocalypse from the fireworks were DEFINITE nightmare fuel.
The whole factory gets rather horrific undertones in Burton's version, especially the melting dolls and the slowed-down song track.
Violet's mother, especially during the press conference. Her wide, unblinking, permanent smile combined with her pink sports suit, blonde hair and excessive make up crosses into Uncanny Valley territory with how much she looks like a psycho Barbie doll.