In the episode "The Eldritch Mist", Shadow Weaver and Castaspella have a brief duel of magic. Castaspella counters each of Shadow Weaver's spells and renders them colorful and harmless. The duel culminates with Shadow Weaver setting a monster on Casta, but it's transformed into a big, smiling teddy bear, which goes after Shadow Weaver and gives her a hug. Shadow Weaver is absolutely terrified.
In the episode "The Stone in the Sword", Adora (temporarily unable to become She-Ra) has to climb up Skydancer Mountain, while Kowl flies up beside her. After she almost loses her footing, Kowl delivers one of his best lines ever: "If you should fall, I'll keep you company all the way down." The dirty look Adora shoots him just makes it funnier.
"Loo-Kee Lends a Hand" has probably the greatest out-of-context Ho Yay moment ever:
Skeletor: With this crystal I can create a portal right into Prince Adam's bedroom!
The entire episode of "Flowers for Hordak" is one hilarious moment after another. Once we see Perfuma dancing with a Hordesman it's pretty much non-stop hilarity.
In "Anchors Aloft, Part 2," Sea Hawk is forced to choose between going after gold thrown into the ocean or pursuing a villain to save She-Ra. He does the latter, which Adora later compliments as noble. It's at that moment that Hawk's first-mate surfaces from the water and reports that he found the gold... right where Hawk said he saw it fall.