Cargo Ship: Marty challenges Jules to make out with a wall-mounted wolf head while playing "Truth or Dare." She gets really into it... leading to the creeped-out reactions of the rest of the cast.
Crosses the Line Twice: The whole movie, but in particular Curt jumping the ravine only to hit the barrier, and the moment the elevators all open unleashing all of the monsters. And then they open again and unleash even more monsters. And then Patience.
Marty. As "the fool," he gets most of the funniest lines, is the only one who figures out the Controllers' game, and turns into the hero in the third act. It's somewhat awesome that the guy who's half-baked into Narnia is the Only Sane Man.
Jules is also very popular, with many calling Anna Hutchison one of the standouts of the cast. A few wish she would have been the lead female instead of Dana.
"Kevin." Whoever he is, he exists as nothing more than a name on the whiteboard (and a brief mention in the novelization) but he has inspired a plethora of trope entries, Epileptic Trees, and Wild Mass Guessing, far more than any other character.
Lots of fans speculate about Mordecai's origins and about whether he'd predicted the film's outcome.
Fanfic Fuel: Well duh. There are hundreds of monsters in the cells below. Plenty of fics involve the protagonists releasing a different monster instead of the Buckners.
Fan-Preferred Couple: Dana and Marty are the subject of the lion's share of shipping fics written about the film.
Genius Bonus: The evil Unicorn makes a lot of sense within the context of the stock slasher movie plot. The Unicorns of classical mythology were actually quite wild and violent - and the only thing that could tame one was a virgin female. One has to wonder how the Unicorn would have reacted to Dana.
Anna Hutchison previously starred in Power Rangers Jungle Fury and this was one of her first roles after this. Her situation is quite similar to actress Cerina Vincent who was in Power Rangers Lost Galaxy and went on to star in the similar film Cabin Fever. Both actresses played "The Whore", both went topless, both were the first to die and both were the Yellow Ranger.
Right around the time the film was finally released Supernatural coincidentally wound up airing an episode with a similar scene of an evil unicorn impaling someone to death with its horn.
The comment about one of the potential monsters being a merman seems a whole lot more funny when you consider the "killer merperson" concept would go on to be used in the Serbian-American horror movie, Nymph.
An undead redneck family who have a thing for pain? Are we talking about the Buckners or the Bakers?
When the kids find the Artifact of Doom museum in the basement, Thor - sorry, Chris Hemsworth is the one who nearly unlocks the orb. (Conveniently, Thor is the first one to bring up the Infinity Stones to the Avengers!)
Older Than They Think: A horror movie about making a horror movie. Characters that revolve around slowly becoming their roles. A higher being out for blood that is only satiated with a new film. We're talking about the same movie, right?
Because if there's anyone who knows how to deal with unimaginable horrors, it is Sigourney Weaver.
We only get to see many of the monsters in brief cameos. One of the most memorable is the evil unicorn.
Rooting for the Empire: Once you know why the kids must be sacrificed, is it out of the question to start rooting for the monsters and/or the organization?
Signature Scene: The entire, ridiculously violent final act. The first shot of the monster's cells opening up and ambushing the facility security team in particular gets passed around often online.
Special Effect Failure: Jules head, when dropped by Dana bounces as you'd expect a light prop head to bounce. Even the sound effects don't match the weight a head should have hitting the floor.
Spiritual Licensee: Believe it or not, this makes for a pretty good adaptation of the SCP Foundation. The main bad guys are a nebulous organization of questionable morality which possesses an enormous catalogue of monsters and other dangerous supernatural items (in this case, horror movie baddies), which it keeps and controls so as to prevent an XK-Class end-of-the-world event. And when the heroes find out about the lengths they're willing to go to, they take one look and say "fuck it, better to let the world end." The similarities get even creepier. S. Andrew Swann's proposal for SCP-001 is that it's the people who are writing the website. In this world. And a very good case could be made that, in Cabin in the Woods, the Ancient Ones represent horror fans.
This was discussed on the site and declared it to be Containment Breach: The Movie — unrelated to Containment Breach, the actual(ly freaky) SCP video game.
Iceburg 7: Though I'd like to hope we wouldn't fail so badly. I mean, people haven't failed that badly at killing five teenagers since Rita Repulsa. emissary666: The idea that an entire site devoted to the prevention of an XK-scenario was so incredibly unprepared for a containment breach was just so shocking to me; especially how easy it was to initiate a breach event when they only kept Keter-level monsters.
However, many other users have pointed out that the SCP Foundation wouldn't be so utterly incompetent as to install a big red "RELEASE ALL THE MONSTERS!" button.
Unless the big red button was an SCP itself that had breached containment?
Some reviewers said they would much rather watch a movie all about the company organising the events than put any major focus on the events inside the cabin.
Some of the other monsters would have made even more spectacular movies. Who wouldn't want to see an evil unicorn terrorizing a bunch of kids? Given what the movie's actually about, though, this is quite fitting; the Controllers are shown to be tired of the "traditional" scenarios and desire something that goes outside the box, but the Ancient Ones want Strictly Formula, and the Controllers know their audience all too well. They're wasting perfectly good plots, and they know it.
What an Idiot: All of the evil monsters can be released with the press of a single Big Red Button. The Controllers are just asking for it! Dana does press multiple buttons before the red one, but they seemed to get released awfully easily.