10 More Horror Movies That Accidentally Filmed Things You Weren't Supposed To See

10. Lurking From Below - The Descent

The Descent is filled to the brim with scenes designed to cause nightmares. The opening jump-scare. The den of bones. The heart-wrenching ending (at least in the British version).

Also, let's not forget about the moment when the Crawler pops into frame unannounced. Even before the main ensemble encountered the carnivorous troglodytes, the tension was through the roof since there was no mistake that something was lurking in the caves. As such, it's tempting to scour through every frame, hoping to catch a glimpse of these subterranean critters.

In doing so, something else entirely can be found hiding in the caverns. Around the 25-minute mark, one of the characters ignites a flare, illuminating the terrain below. 

A humanoid figure can be spotted in the bottom left, which appears to be a Crawler. At first, this seems like a genius usage of foreshadowing, since the prehistoric savages haven't been officially introduced at this point.

In reality, this entity is a crewmember who happened to be on set while the camera was rolling. Reshooting the sequence didn't seem necessary, as this unintended gaffe amplified the creep factor in an already gripping scene.