Not a bad episode. I'm not crazy about the increasing emphasis on the romantic tension, and DI Hunt was clearly introduced as a potential romantic interest for Kate and a further wedge between her and Castle, but I liked the dynamic of a visiting cop coming in and teaming with the gang on "his" case.
The actor playing DI Hunt seemed to have an authentic English accent as far as I could tell, and he even did an authentically terrible Brit-trying-to-sound-American accent, complete with the obligatory Southern drawl. So I think the actor is the real thing. (I can't find any casting info online, and most of the references mistakenly call him Simon Hunt instead of Colin. Perhaps the character's name was changed/redubbed shortly before airing due to legal problems.)
The main thing that bugged me was that incredibly detailed police sketch they got that led them to Hunt. I mean, when Hunt surprised the maid as she opened the motel room door, the way it was filmed, he'd already turned away from her by the time she raised her eyes, and it was pretty dark anyway, so there's no way she could've given such a detailed and accurate description. At most, she would've caught a faint glimpse of his profile. Police sketches are usually a lot more dead-on in TV and movies than in real life, but this was particularly ridiculous.
Couldn't find any info, if that EastEnd Scotland Yard guy will be appearing again, but the trailer for next week looks more promising, as Alec Baldwin will appear.
Adam Baldwin. And yeah, that should be cool, a bit of a Firefly
reunion. It looks like they're going for a bit of a role reversal in their characters, with Fillion playing the character who acts foolish and Baldwin as the one who snarks at him for it.