Nathan Fillion will always be best-loved by nerds for his role as Captain Mal Reynolds on Firefly, but did you know he's also starred in another major scifi franchise? It's called Castle — yes, the show where he's a mystery writer solving crimes with police detective (and love interest) Kate Beckett. Don't believe me? The truth is right here.
1) "Time Will Tell"
A large part of Castle the character's charm comes from his view as a novelist, where he would try to brainstorm theories behind murders that weren't necessary plausible, but would make for good stories — and it was his creativity that inevitably helped Beckett and the other cops solve the case of the week. Somehow that segued into Castle also voicing the most outlandish theory possible, which somehow became a belief in the supernatural. Thus Castle has featured episode where to appears zombies, aliens and even Santa Claus have been involved in murders, although there always ends up being a more reasonable explanation.
And then we come to the sixth season episode "Time Will Tell," in which Doyle (played by Joshua Gomez, best known as Morgan on Chuck) is arrested at the scene of a murder. Doyle claims to be a time traveler, which is too ridiculous for even Castle to believe — until Gomez warns them he's about to be recalled to the future to report to his superiors, and then somehow escapes from a locked holding cell. Castle does not provide any reasonable explanation for this. Eventually we learn that Doyle is trying to protect a scientist whose work is important to the future from an assassin, who was sent from the future to kill him. With Doyle's help, they all catch the killer, who never reveals his origin or any reason why he would want to kill the scientist.
So literally the only theory the show offers for the attempted murder is the time traveling, although Beckett and Castle don't believe it. And while Beckett thinks that Doyle managed to slip out of the holding cell because of a paperwork snafu, it doesn't come close to explaining how he left the station without being seen by a single security camera. The kicker is the final scene, when Doyle rounds a corner, which Castle turns down a mere second after — and Gomez is nowhere in sight. There is literally nothing to suggest that time travel isn't real in the Castle universe, and a ton of evidence to support it. And that's not close to all…
2) "Clear and Present Danger" http://www.youtube.com/watch?v=xhWDg9…
In this seventh season episode, Castle and Beckett investigate a murder of a man who was impaled by his own pool cue; the security camera of his door shows it opening and closing once, but apparently by itself. It appears an invisible man killed the victim, which is bolstered later by the fact that some evidence disappears from the police station, despite Beckett being the only person to have access to it. Castle believes that the Devil killed the man, collecting his soul after selling it for incredible pool skills, because once time travel became real, Castle' the show is pretty much game to believe anything.
Later, Castle is beaten up by an invisible man.
There is literally a completely invisible person running around the Castle-verse. How? Because in Castle, the government has completed completely functional, personal cloaking technology — a suit that rendered its wearer completely invisible. I don't have to tell you that we have not quite achieved this technology in real life yet, although people are certainly working on it. So technically, someone could begin mass-producing the suits in Castle's next episode, and Castle and Beckett would have to fight an invisible army. This sort of stuff never happened in Law & Order.
3) "The Final Frontier"
This fifth season episode is beloved of scifi fans for a number of reasons: the fact that it takes place at science fiction convention, that Stana Katic pretends to be lover of a fictional scifi show called Nebula 9 and even dons some sexy cosplay, and a bunch of Firefly references, as well as nods to other shows. But past that, this is an episode where someone murders someone with a phaser — a laser that literally creates a hole straight through the victims' chest. This is because a dude is making functional replicas of scifi show props in his garage, including phasers.
Given that the energy needed to fire a laser that deadly would requite a power source the size of a truck, it seems that there most have been some kind of massive technological advance in the Castle-verse to allow some nerd to make function death rays at home. So to reiterate, things that actually exist in the world of Castle: 1) time travel, 2) cloaking technology, 3) laser blasters. We're one faster-than-light space travel engine away from Nathan Fillion being able to solve murders on Alpha Centauri.
4) "The Way of the Ninja"
There's literally nothing I need to tell you about the case in this sixth season episode of Castle. Let me assure you that this episode proves that ninjas are real. They can disappear in a flash of smoke and they can jump up large pillars. They are literally dudes in black pajamas with incredible powers and throwing stars, and Castle doesn't even pretend to offer an alternate explanation. There are ninjas. Castle sees them. We see them. Case closed.
5) "Smells Like Teen Spirit"
Yet another sixth season episode, "Teen Spirit" opens unusually for Castle by allowing viewers to see the murder itself. A girl is on a video chat with her friends, when suddenly she appears to be tossed around like a rag doll — definitely not in a manner she could move herself. It culminates when she's thrown against the upper-part of the back fall and falls to the ground, lifeless. It appears that she's been killed by witchcraft, or telekinesis, and since the murder was actually recorded, certainly this is what Castle believes.
Of course, in the end it's revealed that the girl was playing a prank on her friends, and had a boy help her with a harness and some stunningly high quality special effects, including "fishing line and magnets" — and he actually killed the girl after the performance. However, there are several other instances of telekinesis/witchcraft — a table in a crowded school cafeteria flies towards another girl, as well as a massive freak-out at a mob guy's house. Please note that at each of these locations, no one ever found any fishing line or magnets, no any evidence they had been used, and some of these locations were investigated by the NY police. And the murderer couldn't have possibly known in advance where the girl was going in the cafeteria, and thus no amount of fishing line or magnets could have been set to make it work unless it was a phenomenal coincidence.
Castle shows these unexplainable events, and then waves them off by having the murderer explain he did it with fishing line and magnets, and pretending that explains the shit we saw even when it doesn't. It appears telekinesis also exists in the Castle-verse, even if the characters on the show don't want to admit it to themselves. And hey, even if you buy the dude's explanation for his "powers," there's still a guy shown on-screen with the ability to float on screen. I'm pretty sure mutants exist on this show, and Castle's going to get a call from Professor Xavier's School for Gifted Youngsters soon.
6) "The Time of Our Lives"
Airing just a few weeks ago, this episode is Castle's most scifi episode since "Time Will Tell." Why? Well, because Castle gets a hold of magic Incan artifact that literally teleports him to a parallel universe where he doesn't meet or work with Beckett. In this universe, the NYPD aren't his friends, he never wrote his bestselling Nikki Heat crime novels (since he never met Beckett to base the character on), he's a floozy-loving drunk and life is crazy. Basically, it's It's a Wonderful Life, but instead of an angel it's a magic item that helps Castle visit his alternate reality.
At the end, the episode tries to make us pretend that Castle was knocked out by an explosion while holding the artifact early in the episode, and thus his little journey was merely a dream — it's certainly what the other characters think. But Castle the show goes out of the way to discredit this theory, as Castle pinches himself, splashes water on his face, and uses other methods he has successfully used to wake himself up from dreams previously, to no avail. Also, if this is a dream, it it completely and continually consistent with reality — there's no dream logic, no inconsistencies, and everything happens in real time, which is far too linear for any dream. And that's not to mention Castle only "wakes up" from the "dream" when he finds the artifact in the parallel universe and reverses his wish.
The only sensible explanation here is that a magic Incan artifact that sent Nathan Fillion to another plane of reality. Based on the facts the show provides to us, this is the explanation that makes the most sense. Which is insane. But in a scifi world of time travelers, cloaking devices, working phasers, ninjas and telekinesis, it's just par for the course, isn't it?