In "The Flying Smurf", the first (failed) try of the eponymous Smurf to fly is to steal a hen's feathers to make himself wings. Throughout the story, a Smurf appears seeking for his hen. Near the end, the Smurf finds the hen and says "There is it! That's my...! No, mine had feathers."
In "The Smurf King", when the King's Smurfs are searching for the rebels, it's suggested to dig holes to make the rebels fall in them. After digging a hole, one Smurf goes to hide and wait, to fall inside the hole other Smurf had dig, so that Smurf goes to protest for ruining his trap and falls in the hole dug by other Smurf, and so on.
In "The Egg and The Smurfs", one Smurf (possiby an unnamed Early-Bird Cameo of Flighty Smurf) is undecided to what to wish to the egg, and the one waiting behind him tells "if you can't decide, then go to hell". Cue the Smurf surrounded by flames and close to a goat-legged being.
And when Papa Smurf undoes all the wishes, he re-appears with a pitchfork in his hand, looking astonished and telling the others: "You won't believe where I have been."
In "The Smurfs and the Howlibird", when the Smurfs are repairing a crossbow to use against the Howlibird, Papa Smurf needs a nail and calls a Smurf. When he notices he called Clumsy Smurf (who always brings the wrong thing when asked), Papa Smurf is Genre Savvy enough to know that if he asks for a nail, Clumsy Smurf will bring him a screw, so he asks him for a screw... and Clumsy Smurf brings him a nut.
In "The Weather-Smurfing Machine,":
The bit where the weather house figures fight each other.
During their fight over the weather changing machine, Poet and Farmer are fighting with snow around them:
Poet: Sun! Sun! Sun!
Farmer: Rain! Rain! Rain!
Poet & Farmer: Snow!?
Brainy trying to open the umbrella only for it to stop raining just as he opens it. When he closes it, the rain starts again and Brainy can’t get the umbrella to open again.
In "Smurf Versus Smurf", when a North Smurf makes a divisory line between the halves of the village, he marks it inside the house of a Smurf. The poor Smurf must adapt to the idea of crossing the line (and changing his speech patterns accordingly) to do the most mundane tasks.
In the cartoon special "The Smurfic Games", a dividing line separating the east end of the village from the west end gets painted right over Clumsy.
In "The Smurflings", the de-aged Snappy Smurf passes close to Grouchy Smurf:
Snappy Smurf: AND I HATE BIG SMURFS!
Grouchy Smurf: Uh? but I haven't said anything yet!
Snappy Smurf: But you were about to, weren't you? I could tell.
Grouchy Smurf: How did he guess? (In thoughts) I hate Smurflings.
In "The Black Smurfs", one of the titular Black Smurfs painted himself blue to not get targeted with the cure... And gets promptly bitten by another Black Smurf trying to spread The Virus.
Gargamel's evil plan to attack the Smurfs in "Romeo and Smurfette" is... starting a Ship War!
In "Foul Weather Smurfs," the bit where the weather house figures fight each other.
During their fight over the weather changing machine, Poet is on top Farmer (at arm's length), flailing both arms and legs with snow around them:
Poet: No! Sun! Sun! Sun!
Farmer: Rain! Rain! Rain!
Poet & Farmer: Snow!?
Smurfette complaining about her laundry getting all wet because of the rain at the beginning of the episode. Clumsy decides to help her but slips on a puddle, getting mud all over her who she thanks sarcastically. Cue Brainy making a comment:
Brainy: Now did you see that! Isn't that the smurfiest thing you ever-
*Lightning flashes and boom of castle thunder causes Vanity to jump in Smurfette’s arms*
Vanity (high-pitched): SCARED!
At the end of the episode, Poet decides to write "An Ode to the Rain.":
Poet: How am I supposed to finish my new "Ode to the Rain?"
*Jokey, who's sitting on a tree branch above, pours water on top Poet's head with a watering can*
Jokey: That better?
*Everyone but Poet laughs with Jokey*
Poet: Well, at least it's ecologically sound! Hmph!
Hogatha not noticing that she's wearing a fake beard until she looks in the mirror and sees it when she casually says, "I have charm, I have beauty, I have a beard..." in "Hogatha's Heart Throb."
In "Chip Off the Old Smurfs," Handy and Painter are arguing over Baby Smurf's future when Poet Smurf walks in to find Baby Smurf singing a song to himself, in baby talk, and rhyming the last syllable as he sings. Poet's response? "Why, listen to that, free verse!"
Smurfette's idea of a honeymoon with Hefty in the cartoon special "Smurfily Ever After".
In the end of "Queen Smurfette," after nighttime finally befalls Smurfs Village in due to it being a very long day, everyone is in bed, tired and exhausted. It doesn't take long before the sun rises again as the Shade of Night rolls itself back up, and the Smurfs are treated to an unwelcome wake-up call by Harmony:
Smurfs: Aaw, smurf it off, Harmony!
Also, when the Smurfs are singing Smurfette “happy birthday,” it suddenly gets dark. The Smurfs notice and quicken the song to finish it.
In "Poltersmurfs," after the titular prankster little spirits are let out, a trio of poltersmurfs are playing music off key in Harmony’s house just as badly as him . . . in which the toned deaf Smurf is tapping his foot, commenting that it got a smurfy beat, enjoying it instead of freaking out like the others. It's then when he asks if they can dance to it is when the spirits start throwing things at him. After one of them slams an oversized tuba on him goes running out asking for help.
Also, while three of the poltersmurfs are trashing Painter’s house, one is having a sword fight with Painter, but with paintbrushes:
Painter: Take deez . . . an' deez (steps into bucket of green paint) It iz no uze! (Jumps out of window) Everysmurf fer himself!
When Brainy and Greedy, who's been eating the “joke candy” on the way to Dark Castle where the titular spirits came, close the slab of rock trapping the poltersmurfs once more. Greedy begins talking, emitting his garlic and onions breath onto Brainy:
Greedy: That was close!
Brainy: (waves hand in front of face) Eew . . . you're too close!
Greedy clamps hand over mouth.
At the end of the episode, after Jokey apologizes Brainy starts getting into a lecture about something scaring him, only to stop when he hears moaning. Thinking it's the poltersmurfs, Brainy hides behind Papa Smurf. As the moans get louder, the camera gets to a faraway shot of Papa Smurf, Grandpa, Jokey and Clumsy looking at Greedy sitting on a bench, retching in pain for eating too much joke candy.
The most humorous character by far in an otherwise Strictly Formula film must be Narrator Smurf, who is a literal Interactive Narrator — that is his actual job. In the Final Battle with Gargamel, he lampshaded the fact by declaring in his "announcer voice" that he cannot stop talking like this.
Gargamel, ensconced in Rikers, attempts to pull a Gandalf ploy by commanding a moth to bring him mighty eagles so that he might fly out of there. Shortly thereafter he's being menaced by some other prisoners when his ticket out returns... with a swarm of flies. For extra bonus funny, once he gets over the initial disappointment he doesn't seem to mind that much. Not to mention that it works.
Three words: "Are you dead?"
Gargamel talking to several people on the street about the Smurfs:
Gargamel: Excuse me, have you seen any little blue men?
Businessman on phone: Sure, what price are we talking about?
Gargamel: You're selling them?
Girl on phone: Yeah, I'm giving it to Lily.
Gargamel: Who is Lily?
Guy on phone: She's only the hottest girl in my apartment!
Gargamel: What does the temperature of Lily have to do with Smurfs?
Later he asked a hobo (whom he identified as a "peasant") if he's seen little blue people: