The opening has a few moments, but the part in the ice cream parlor takes the cake. It shows Starlight and Bon Bon preparing the ice cream, only for the latter to accidentally squirt some ice cream on Clover's face. It's Bon Bon's face that sells it.
In the episode "Battle of the Bands", Melody's younger sisters open up a sandbag and play with it like a sandbox. This makes a background display topple over and fall on some performers.
"Stand by Me": Teddy getting his hooves stuck in a wastebasket and later falling in the lost and found box, requiring Sweetheart to pull him out both times.
"The Tea Party":
The entirety of the "Boys, Boys, Boys!" song, but especially the girls' reaction to Ace sweating on the exercise bike.
When the girls find that a group of ponies has stolen the furniture in the abandoned house:
Starlight: As chairpony of our tea club, I hereby table our vote on the boys. Clover: What table? It's gone!
During the "Home Alone" Antics, Clover steps on the cream she placed on the stairs. She slips and falls down them one by one.
When the girls bombard the "thieves" with jelly, one of them licks it off his face.
The girls sabotaging Melody's dress rehearsal in "The Play's the Thing". Melody loses it when she can't open the door to the prop castle.
Melody: OPEN, DOOR! (rips the door off and the castle collapses)
Lancer's expression when Bright Eyes ties a bib around him.
"Blue Ribbon Blues": Teddy getting attacked by hens when he tries to collect eggs. They chase him outside where he trips over a wheelbarrow and slides in some mud into a pig pen.
In the episode "Sister of the Bride", near the beginning, Sweetheart comments on how romantic the wedding is... falling on her ass in the process, complete with a comedic 'boing' sound effect and dust being spread around her.
After the flowers they ordered were crushed, Meadowlark hoped that Cheval will love the flowers from the garden instead.
Sweetheart: Cheval! The wedding! (lays on the floor crying, believing Cheval is cheating on Meadowlark) Patch: Don't mind her. She always cries at weddings.
Lancer getting back at Teddy pranking the girls in "Happy Birthday, Sweetheart":
Teddy: Nice move, Dream Team! What do you call that one? (laughs) Lancer: Well, I call this one "Squirt Teddy with the Hose"! (which he does)
In the episode "Bon Bon's Diary":
Bon Bon's Mother: "Hello, dear. How did you do on the maths test?"
Bon Bon: "I got an A "*sobs*."
Bon Bon's Mother: "Bon Bon, are you all right? If you got an A on your test, then why are you crying?"
Bon Bon: "Because...because I'm so happy!"
Bon Bon's Mother: "Then try not to be quite so happy, alright?"
Patch kicking a soccer ball in Ace's face in "Just for Kicks".
Mrs. Sunbright's Aside Comment in "Ponies in Paradise": "Sometimes these mainland ponies sure act strange!"