Author Filibuster: The interviews with the (fictional) cast members sprinkled throughout sometimes act as this for ridiculous things (for instance, talking about a foundation to help underprivileged children learn psychokinesis). Also, it's occasionally mentioned that Garth Marenghi fills his novels with them. On one occasion, the show's action stalls to explain why buying non-brand-name batteries is a bad idea.
Dean is, in his own words, "not an actor" and simply blurts out his lines with no understanding of what he's saying. He also frequently glances off camera at his lines or at the camera itself. There are also lots of obvious edits in his longer lines, making it clear that he couldn't get out his entire speech in one go.
Todd has a habit of drawing out vowels and hams up every line like Tom Baker on one of his drunk days. He also has a tendency to break Lip Lock when re-dubbing his lines. He also strikes a pose whenever entering a room or turning a corner, another trait lifted from Tom Baker.
Madeleine responds to everything with breathless shock and admiration.
The "labourers" (including Graham Linehan) react to everything with blank expressions and bored voices: "Let's do it here. I'm really horny." They often move mechanically, apparently taking great concentration to hit their marks, and take their cues much too late.
In general, characters sometimes talk extremely quickly, rushing through their stilted dialogue. The cook, played by Stephen Merchant, is a notable example.
The Temp in "Hell Hath Fury" is, by comparison, a rather good actor who has simply been given bad material to work with.
The security guard in episodes 3 and 6 is played by Graham Linehan.
Captain Obvious: "I ran the only way I knew how. By placing one leg in front of the other in quick succession."
Cardboard Boxes: Used prominently in "The Apes of Wrath" - Dagless shoots a shelf (apparently) causing Sanchez to be crushed by an avalanche of boxes. A little later on, Dagless and the Apeoid go crashing into a strategically-placed mountain of the same boxes in the middle of a forest.
Celebrity Paradox: People read Garth Marenghi's books in Darkplace. This can be mainly put down to his enormous ego.
Da Chief: Thornton Reed is clearly written this way, but due to Dean Learner's nil acting skills is anything but.
Deleted Scene (in-universe): Apparently, Garth was only willing to cut one scene from over 50 episodes of the show he had created. This one scene is a flashback/dream sequence set in a Scottish chip shop.
Dr. Rick Dagless M.D.: The doors of Darkplace were open. Not the literal doors of the building, most of which were closed. But evil doors. Dark doors. Doors, to the beyond. Doors that were hard to shut because they were abstract and didn't have handles. They were more like portals really.
Spoofed as the credits list the opening tune as being "based on melodies whistled by Garth Marenghi".
"One Track Lover", an original song from the broccoli episode, is a straight example, sung by Matt Berry.
Don't Explain the Joke: Marenghi's narration frequently steps in to explain something that only an idiot wouldn't understand.
Double Entendre: Quite a few start springing up once the term "Homo Erectus" gets used.
Dr. Rick Dagless M.D.: Sanch is regressing to Homo Neanderthalenis [sic]. Right now, Sanch, you're Homo Erectus, but who knows how long you've got.
Dr. Lucien Sanchez: I appreciate you being straight with me.
Thornton Reed: And you and I are Homo Sapiens?
Dr. Rick Dagless M.D.: Correct.
Thornton Reed: But if we're all basically Homos, shouldn't we get along?
Thornton Reed: Come on, you two queers! We need to lick this problem before it turns around and slaps us in the nuts!
Dropped a Bridge on Him: The (fictional) actress, Madeleine Wool, who played Liz disappeared without a trace after the filming of Darkplace. She is (emphatically) presumed dead by her fellow cast members. Dean Learner speculates that she's "buried somewhere in the Eastern bloc. If she got a burial." The awkwardness of the remaining cast members around the subject and the fact that they're all incredibly shady to begin with suggests that there's a pretty sordid story behind the disappearance.
Dull Surprise: When an actor isn't being a Large Ham or outright Chewing the Scenery, they're this. Especially true of Dean Learner (who isn't even a professional actor) and the extras. A notable example is in the "cast interviews" for Episode 4, revealing why Madeleine Wool hasn't appeared in any of them - she went missing and is presumed dead. This is, of course, mentioned nonchalantly in a single line from Dean.
DVD Commentary: Done by Garth, Dean and Todd. It quickly becomes evident that Todd has never actually watched the show and only vaguely remembers filming his scenes. He's not impressed by it. They also (loudly) eat toffees and drink beer during the commentary.
Eureka Moment: Spoofed in "The Apes of Wrath" when people start devolving into monkeys due to obviously green contaminated water. Dr Dagless suddenly puts all the pieces together — the fact that his friends turned into monkeys after drinking a cup of water, the only two people who haven't turned into monkeys aren't drinking the water, and that the water's a sickly green color — and concludes that he's thirsty.
Filler: Dean Learner states that so much slow-motion footage was used because the episodes often ran several minutes short and had to be padded out somehow. The fact that most of the dialogue is delivered in a rushed garble probably explains why each episode winds up short.
Filming For Easy Dub: There's a sequence in which the camera cuts back and forth between a wall and a potted plant while Looping Lines of the off-screen cast give an Info Dump on the plot so far. It's obviously added in post to correct some serious plot problems.
Foreshadowing: Why doesn't Madeleine appear in any of the interviews or commentaries? She went missing after the filming of the show and is presumed dead.
Fun with Subtitles: If you have them turned on, when the intro music starts the subtitles display "CHEESY 80S SYNTHESISER MUSIC".
The Scotsmen have all their lines subtitled despite not being very difficult to understand.
Get a Hold of Yourself, Man!: Rather than slapping Liz whenever she's "hysterical", Dagless punches her in the face. It's obvious Garth has "issues" with the fair sex. The fact that Madeleine's Dull Surprise acting means she looks as hysterical as someone on valium doesn't help much.
Dr. Liz Asher: Thanks, Rick. I needed that.
A Glass in the Hand: Thorton crushes a styrofoam cup in his hand, the same hand that was holding a shovel two seconds ago in a previous shot.
Hall of Mirrors: Clearly the budget wouldn't stretch to an entire hall, but we do get the tense shoot-out in the "water and mirror storage room." Well, where do you think hospitals store their water and mirrors?
He's Got a Weapon!: Some obviously dubbed-in dialogue has Thorton yell, "He's got a stick!" to explain why Dagless is suddenly holding a stick in the next scene.
Ivy League: Liz Asher, in a brilliant bit of intentional research failure, went to "Harvard College, Yale."
Jerkass: Marenghi is bad, but Dean Learner suffers from so much Values Dissonance that he borders on Sociopathic Hero. Especially as it's implied he killed the person who financed the show (Achmed who was interested in "moving pictures" and very "sadly" was shot in his flat), Garth's second publicist and Liz's actress.
Living Prop: An extra with noticeable red muttonchops serves a number of different bit roles throughout the show.
Looping Lines: Often featured and played for comedy. The looped lines are much louder than the normal dialogue and stuck in regardless of whether they match the actor's lips or if his mouth is even moving at all. Most of the additional dialogue seems to be added to add exposition or address continuity errors.
Sanchez: Look, it's Jim! He's been hit by the mist, though he's still alive, unbelievable as that seems!
Love Triangle: Sanchez likes Liz, but she's clearly enamoured with Rick. Unfortunately, Rick is already in love with himself.
Mr. Exposition: Naturally, Dr. Rick Dagless, MD. In one episode, the plot was so badly written that by the end of the show Garth has to talk non-stop for nearly a minute in order to explain what the hell has been happening. Made even more hilarious when it becomes obvious that this scene was never filmed, as we hear Garth delivering a voiceover at breakneck speed whilst the screen displays stills of inanimate objects from Thornton's office.
Missing Episode: After Channel 4 cancelled the series, Garth Marenghi stated that he may have taped over one of the 44 or so remaining in-universe episodes with one of The Thornbirds.
Mr. Seahorse: "Look at that poor man, he's been screwed by a giant eyeball and now he's giving birth."
Dr. Rick Dagless M.D.:[narrating] Reed told me everything. How the monkeys now ruled Darkplace. How they'd taken over. Thornton Reed:[flatly] They've taken over. Dr. Rick Dagless M.D.: Oh no. Oh Jesus. They've taken over. They've taken over! Thornton Reed: I know!
Dean Learner: He had a very ambitious script. I said, "Garth, this is a very ambitious script for the money we've got. Seeing as we've got no money, it's extremely ambitious". We were filming it in my garage. I had a big garage, but still it was ambitious to film a TV show in a garage.
Pixellation: The Eye Rape scene. Parodied when Dean then goes into a long rant about it: "I think it's disgusting that we had to pixellate out an erection. I mean we've all got one. I could have one right now and you wouldn't know. I mean, I don't, but..."
During one episode, the characters go into a lonnnnnng tangent about the superiority of name-brand batteries such as Duracell or Eveready over cheap "£1 bags" of batteries. Note that Ofcom didn't like this kind of thing at all.
Parodied again when Dagless picks up a Marenghi novel and spouts off several lines of dialogue concerning how he had "misjudged the genre".
Parody Sue: Dr. Rick Dagless, M.D. He is more specifically a parody of a real Sue: Peter Rickman of Kingdom Hospital. Aptly, Garth Marenghi is not a small bit reminiscent of Stephen King himself.
Rule of Cool: Sometimes merely otherwise inexplicable (why are doctors carrying around guns?), sometimes clearly a product of Marenghi's fanboyish replication of US media (the English Dag having fought in Vietnam "for [his] country").
Sawed-Off Shotgun: Thornton Reed's weapon of choice for any situation, even those that don't require any firearms. Especially those that don't require any firearms.
Shown Their Work: Parodied, when Rick cradles a dying minor character in his arms and it's obvious that the only dialogue Garth could think of was a very skimpy rework of the research he'd done to explain the character's accent:
Dr. Rick Dagless M.D.:[tenderly] What's your name, son?
Dr. Rick Dagless M.D.: That's a strange name for an American.
Clive: I'm from Bermuda.
Dr. Rick Dagless M.D.: Oh, that explains it. British principality.
Clive: It's actually a dependent territory.
Dr. Rick Dagless M.D.: What's that?
Clive: The Queen appoints a Governor General in charge of internal security and external defence but she's still the de facto sovereign.
Soul Brotha: Thornton Reed is probably intended by Marenghi to be played as a Soul Brotha; he says in the first episode that if Dagless doesn't pull through, "My ass is grass! And he (Won Ton)'s got a lawn mower, ya dig?". Dean Learner cannot quite pull this off.
So Unfunny It's Funny: The characters often spout what are supposed to be witticisms, and there are a few moments of friendly playfulness between the doctors that are intended as comic relief. They're all so cliched or poorly executed that it's funny.
Space Whale Aesop: "I know writers who use subtext and they're all cowards. OK? What I was asking in that scene is: what if politicians continue to pay doctors peanuts, could they literally turn into monkeys? And no-one's asked that before."
Darkplace itself bears something of a resemblance to the Gelliant Gutfright sketches from A Bit Of Fry And Laurie, such as "The Red Hat of Pat Ferrick".
Spontaneous Human Combustion: Rick Dagless's old college buddy spontaneously explodes (though his head survives long enough to ask Rick to finish him off); in the commentary, Dean Learner mentions that while filming the scene it was clear to everyone that "someone close to Garth had exploded" in real life.
Status Quo Is God: The authorities seem to have absolutely no interest in exploding patients, ape outbreaks, cosmic killer broccoli and murderous Scottish ghosts, leaving our heroes to get on with fighting the next Monster of the Week.
Techno Babble: Used frequently to justify the atrocious plots; most egregiously with Gavin, the hospital gas expert, and in the Apes of Wrath to explain how a scientist was able to turn people into monkeys.
Too Stupid To Live: In "Hell Hath Fury" Sanchez fights off the items coming to life with his pistol, which then comes to life. He then wrestles it to the ground. Only to pull out another pistol and shoot his pistol, and then that one comes to life as well and chases him down the hall.
Troperiffic: Almost every trope the show invokes is done so deliberately in order to parody it.
Thornton Reed:[picks up phone] Uh huh. Bye. [hangs up]Good gravy. A small bunch of objects are flying of their own accord in E Wing! [picks up non-ringing phone, then hangs up without saying anything] And apparently more objects are heading this way! [hesitantly, in the direction of the telephone] Good...bye...