"Willy Wonka and the Chocolate Factory" is not a horror movie. Sure, much of the plot revolves around an eccentric recluse who lures unsuspecting children and their guardians into his chocolate factory to endure potentially life-threatening tests so that he can secure an heir. And yes, the factory is powered by the slave labored of musically inclined, orange little people, but it is still a well-loved children's movie that has captivated audiences for 50 years since its initial release in 1971.

Obviously, its status as a classic family film does not negate some of the more disturbing elements of the film, and vice versa. This brings me to one of the most arguably unsettling things about "Willy Wonka and the Chocolate Factory": the infamous tunnel scene. If you've seen the movie at least once, I'm sure you know the one.

The scene has been regarded by many as one of the most frightening scenes in a non-horror movie, and I think viewers can all agree that it is at least objectively jarring, and as it turns out, viewers weren't the only ones who found themselves unsettled or outright terrified by the scene — even the actors found themselves unsettled on set that day.

The Scene

Willy Wonka (Gene Wilder) himself ushers everyone onto his boat and proceeds to recite a strange poem, beginning quietly and then increasing both the volume and fervor of his recitation until it becomes a frightening display of insanity. As if that isn't scary enough, this display is accompanied by the rapid flashing of lights as disturbing imagery — like that millipede crawling across a man's face — flickers across the screen. If you need a visual refresher, here is the scene in question:

That's some creepy s***, so it makes sense that viewers would be scared, but why would this frighten the actors? Surely they knew what to expect, right?

They didn't. The stars of "Willy Wonka and the Chocolate Factory" had some understanding of what was to come for the boat scene, but they weren't prepared for the intensity of Wilder's delivery. The result is a sensory nightmare coupled with an over-the-top performance from an extremely dedicated actor whose costars weren't 100% privy to how things would play out.

So Here's The Thing…

The fear of wondering if they were actually watching their talented costar lose his mind in real time combined with the disorienting visual effects resulted in authentic reactions from the other actors present. According to Julie Dawn Cole, who played the character Veruca Salt, there was no indication that he'd be going full crazy with his performance that day:

"Gene wasn't a method actor and did take direction, but he was always creating his own thing. We never quite knew what we were going to get from him, particularly the boat scene in the film, when he went slightly loopy— whether that was improvisation or not I'll never know, but we certainly didn't see it coming!

The lack of forewarning meant that the actors, child and adult alike, were all genuinely just as terrified, shocked, and unnerved as audiences continue to be half a century later.

Knowing this makes the scene all the more interesting and unsettling in retrospect, and it doesn't take away from the fact that "Willy Wonka and the Chocolate Factory" is still a charming family film, even if some of the imagery has evoked a visceral response in viewers.

Personally, I found the juicy swelling of Veruca Salt to be much more horrifying than the tunnel scene. To this day, I can still recall my childhood fear that she would burst, saturating everything and everyone around her with organs, tissue, and blueberry juice. There's also the anxiety-inducing "fizzy lifting drink" scene wherein Charlie and Grandpa Joe narrowly avoid being violently sliced to pieces by large metal fan blades. And the fact that everyone was pretty chill after watching the near-drowning of Augustus Gloop, considering that nobody decided to get the hell out of there upon seeing Wonka's apathetic reaction to a kid nearly dying in his facility. Never mind the impromptu musical numbers about each child's brush with death, sung by a chorus of tiny slaves.

Although it contains some questionable elements that can quickly become disturbing upon further examination, "Willy Wonka and the Chocolate Factory" is a film with a lasting legacy that audiences from all generations can't get enough of. Maybe we'll even learn more about the notorious tunnel of terror in the upcoming prequel, which will star Timothée Chalamet as a younger version of the unhinged chocolatier.

Read this next: The 15 Best '70s Horror Movies Ranked

The post The Unsettling Reason Willy Wonka's Tunnel Scene Feels So Terrifying appeared first on /Film.