Negative Continuity: A number of episodes end with Courage losing or the characters dying, yet they're back to Square One the next week. Even the original short film featured Eustace turning into a monstrous alien chicken and then getting vaporized. None the less, there's still a few reoccurring villains in the roster providing continuity in spite of it all.
The season 1 finale "The Great Fusili" is probably the most glaring example of this and has caused quite a bit of controversy.
New Job as the Plot Demands: The recurring red mustache guy holds many different jobs depending on the episode. Many of his jobs include working as a Nowhere police officer, an archaeologist, a captain, a pilot, a New York police officer, a ranger, a general, a pirate, and a mayor.
Nice Guy: Courage himself, and one of only a few in the entire series.
Nightmare Face: The violin girl in "Courage in the Big Stinkin' City".
No Celebrities Were Harmed: Snowman had Sean Connery's speech pattern so downpat, that some fans thought Sean Connery actually did his voice (but it was, indeed, Paul Schoeffler).
In the episode "House Calls", the Bagges' new neighbor, Dr. Von Orbison, is almost a dead ringer for Roy Orbison.
No Sell: There's Eustace's immunity to Dr. Zalost's unhappy cannonballs because he's immune to emotions. He was also unaffected by the Cruelty Curtain (because he's already a jerk), as well as Muriel and Courage due to her fabric softener, or Incorruptible Pure Pureness, or some combination of the two.
Nothing Is Scarier: The ending to the Le Quack episodes ends with the titular villain escaping from his confinement and he always leaves behind evidence as he goes such as a police van crashing with no officers in sight, and a prison on fire with no signs of other convicts, though it's never explained how he managed to escape every time. Since he usually fights Courage through the means of cartoonish antics, this just makes the endings even scarier.
"You see that door? You wanna know what's behind that door? You don't wanna know what's behind that door. See those bones? Wanna know what made those bones? You don't wanna know what made those bones."
Offscreen Moment of Awesome: In "The Mask", Courage takes down two dogs. We don't see what he did but he apparently needed explosives and several arrows.
Off with His Head!: The premise of "The Revenge of the Chicken from Outer Space" episode, which ended with Eustace being seen that he had fell victim to the trope.
Eustace, Muriel, and Courage are decapitated by the vengeful ghosts of the vandals in "Windmill Vandals", although thanks to Rule of Funny they inexplicably survive and their bodies simply reattach their heads as if they were dolls. In universe, this may or may not be Justified due to the supernatural nature of the ghosts and their weapons.
Ominous Pipe Organ: This type of music plays in a few episodes, beginning with Courage in the Big Stinkin' City. Noteworthy in that they don't use it unless something very creepy and supernatural is happening. The song also contains church bells and a choir.
The Stitch Sisters' Leitmotif also makes use of this trope, although it's more quiet and somber than the song mentioned above.
Eustace getting the bad end of the deal and suffering a horrible fate.
One-Woman Wail: "Doc Gerbil's World", where the final boat chase between Doc Gerbil and Courage is accompanied by almost no sound other than this. It simultaneously comes off as Soundtrack Dissonance and Crowning Music of Awesome. The only reason it's Dissonance is because said chase scene was between a plaid-wearing gerbil and a pink dog on jet-skis.
In the early episode "The Shadow of Courage", whenever Muriel would catch Eustace abusing Courage in any way, she would run at him with her rolling pin, accompanied by a triumphant, operatic one-woman wail.
O.O.C. Is Serious Business: The episode Remembrance of Courage Past features Courage in a catatonic state after seeing his parents in a milk carton. He remembers how his parents were taken to the moon by the evil vet, and stayed at the same spot the whole night, not moving an inch. Eustace tries scaring him with his usual "BOOGA BOOGA BOOGA!" mask, but this time, Courage does not react. 'Muriel's so worried about that that she decides to take him to the vet.
Opaque Lenses: Muriel & Eustace, as well as Eustace's whole family. Similarly, all of the recurring normal, non-villainous human characters except the General had their eyes obscured. This seems to emphasize Courage's status as a Cassandra type, as nobody else sees what's obvious to him. Subverted in the Hothead episode (though it's fairly surreal looking).
Pass Fail: Kitty's mask and dress are a fairly obvious metaphor.
Pet the Dog: Horribly, horribly subverted, in "The Precious, Wonderful, Adorable, Lovable Duckling", where a duckling thinks Eustace is its mommy. Eustace tries to be a good mom, but the bird secretly wants to kill Muriel. Eustace doesn't seem to care about Muriel (then again, did he ever?), even if the bird blatantly tries to kill her. It doesn't help the bird is probably as bad as Eustace.
This ended up with the pair being blown to the moon (in Muriel's place), and each pairing lives quite contentedly.
Eustace also has a few more genuine moments of this. For example, in "The Mask", he seems genuinely concerned about Kitty's past, and reassures Muriel when she worries about her faults.
Reluctant Monster: Courage encounters a few of these. Most notably, Bigfoot, who Courage ends up making friends with, and Carmen, a one-eyed sea serpent who kidnapped Muriel, but only because she wanted an audience to show off her beautiful operatic singing voice.
Reused Character Design: John Dilworth admitted that Katz is a taller male version of his cat character from The Dirty Birdie.
Rogues Gallery: Amongst the threats Courage has squared off against, the recurring ones include Katz, Le Quack, the Chicken from Outer Space (and his son(s)), The Snowman (though he later reforms after Courage helps him), and the film director Benton Tarantella. The evil vet also could be included, considering how much impact he's had on Courage's life.
Rule of Funny: Determines whether Courage can speak or not in each episode.
Rummage Fail: Whenever he'd look through his impossibly large, nonexistent "pockets", he'd normally have to pull out three or more objects until he got what he needed, at which point he'd stuff it all back in.
Sand Is Water: One episode has the titular character forced by Eustace's mother to hunt a sand whale, who is trying to get his accordion back from Eustace's mother. And Courage is forced to row a boat in the sand. Another slight subversion, considering that the ground only worked like water for the sand whale, and not the rowboat.
A scare chord accompanied almost every title card.
Whenever Katz made an appearance. You could tell a few seconds before he was actually shown, by the creepy beat that suddenly started playing. And it kept playing. Until it could cause shuddering years later.
Scenery Porn: A lot of the shots of the farm house either at night or at sundown are awfully pretty for a Crapsack World. The show uses a technique of overlaying photos with animation, so the skies you see are (mostly) pictures, although exaggerated or altered.
Schmuck Bait: Courage's computer enjoys baiting him with false advice that results in him being tarred and feathered among other things.
Second Person Attack: In "1000 Years of Courage". Courage picks up a banana, attempting to eat it, but it turns out to be a living baby creature. Courage makes a dash for it as its mother hits him over the head twice with her purse.
The Secret of Long Pork Pies: Subverted in "Heads of Beef". When Eustace takes Courage to a new fast food restaurant, Courage looks around, and notices many strange things that lead him to assume that the restaurant's owner, a Pig Man named Jean Bon, is making his hamburgers out of human flesh. It turns out that everything Courage saw was just an unfortunate coincidence. Jean Bon's burgers really are made of beef, and he doesn't mean to hurt anyone.
Something Completely Different: The show was most known for its various monsters, but certain episodes went for a Miyazaki-esque angle ("The Last of the Starmakers"), gangland drama ("The Mask") or something else still ("Mother's Day").
Space Whale: A dangerous predator, in "Last of the Starmakers".
Strong Family Resemblance: Eustace is a carbon copy of his parents. Lampshaded in "The Sand Whale Strikes", when the Sand Whale has confused Eustace for his father, Ickett. Eustace pulls out a picture of his father (who looks exactly like him with a huge beard) and says "I don't see the resemblance."
Stylistic Suck: The flashbacks in "Remembrance of Courage Past" have choppy animation.
Super Strength: Eustace is amazingly able to eat just about anything with no problem, despite having no teeth whatsoever - this includes lobsters still in their shells, raw carrots, candy canes, and other hard/crunchy foodstuff.
Courage basically gave himself this with a 5-second workout during "The Forbidden Hat of Gold", muscles and everything, just to rip open the door to the dungeon he and Eustace were thrown in, only to promptly "unzip" his muscles like they were a costume immediately afterwards.
Surreal Humor: While most of the comedic moments in the show are normal enough, there are situations meant to be taken funny, but come off as so bizarre they still make you laugh while scratching your head. A quiet moment in Dr. Le Quack, Amnesia Specialist has Muriel, suffering from amnesia, quietly strumming on a sitar. No context, no warning, yet it comes off as charmingly and strangely hilarious.
Surreal Horror: Especially with the blue fetus thing in Courage's dream in the grand finale, a perfect example of Uncanny Valley involving computer animation, and the Synchro-Vox tree and moon qualify as well.
Suddenly Voiced: The tiger from "Squatting Tiger Hidden Dog". Also Courage, as a recurring character trait.
Synchro-Vox: The Spirit Of The Harvest Moon and The Magic Tree Of Nowhere use this technique.
Talking Animal: And boy are there a lot of them! Strangely, Courage talked frequently in the early episodes, but later became a Speech-Impaired Animal over time. This is actually a result of Executive Meddling, CN forced Dilworth to give Courage less talking lines as they felt he was funnier as a babbling animal. The latter is somewhat subverted at one point. Realizing he can't talk to Muriel directly, he runs to a payphone and calls her.
Theatre Phantom: The Great Fusilli, a crocodile who ran a stage that transforms its actors into puppets. Ironically he falls for his own trap when he mistakes Courage for a Theatre Phantom.
Trademark Favorite Food: Throughout much of the series, Courage loved liver, yet in "Ball of Revenge" it's implied he hates it and the series finale shows fried chicken dumplings as being his favorite.
This actually may keep in line with continuity, because there is an episode where Muriel tells him he can no longer have liver (presumably due to what she perceives as nightmares).
The Bagges seem to really love their pancakes, they have them almost every morning for breakfast.
While Eustace in general was a Big Eater, by Season Three his favorite food was "chopped meat".
Vocal Evolution: Eustace's voice has become noticeably deeper halfway through Season 3. This was due to his original voice actor Lionel Wilson retiring due to ill health, and was replaced by Arthur Anderson for the rest of the series.
Voice Actor: Averted. With the exception of Lionel Wilson, and Season 1 featuring Jim Cummings (Fusilli) and Kath Soucie (Little Muriel), most of the voices on this show were performed by local New York City-based stage actors, or Stretch Films employees.
Weird Weather: "Little Muriel" ends with a sudden tidal wave washing over Nowhere, which is entirely illogical, considering Nowhere is in Kansas, nowhere near any body of water large enough to cause a tidal wave to surge over the entire town. Courage even lampshades this by remark, "Crazy weather we've been having, huh?"
Why Don't Ya Just Shoot Him?: Katz frequently plays this straight with bizarre death-traps that would kill Courage indirectly, although, when the cards are down, he often subverts this by attempting to strangle the dog with his bare paws.
In "Big Ball of Revenge", the littlest toe points out how silly this would be, and gets a Dope Slap for his trouble.
Wild Take: Courage's tendency to scream in terror actually saved him in a later episode when he screams so loudly for so long that he shatters the foundation of his house, sending a team of series villains plunging into a bottomless pit.
Woobie, Destroyer of Worlds: Snowman. True many of his plans would cause a lot of death and destruction, but its all entirely motivated into saving his species.