"Rowsby Woof and the Fairy Wogdog" is filled with funny moments, most of them potshots at dogs (whom the rabbits understandably don't like), such as Rowsby's pride in his own abasement to "Queen Dripslobber" (accompanied by "her noble attendants, the fairies Postwiddle and Sniffbottom.").
The Running Gag of Bluebell starting some ridiculous poem only to have Hazel finish it with a biting final rhyme.
Bluebell: "How comforting to be a slug! Among the dandelions so snug..."
Hazel: "And feel the blackbird's sudden tug."
Leading up to that he's complaining about how much his feet hurt, and announces cheerfully that since slugs don't have legs, he has decided to be one.
Speedwell's Story from Tales of Watership Down is pretty much one long Funny Moment with its complete surreal nonsense, though the highlight has to be the otherrabbits'reactions. The entire thing is essentially one long troll to see who breaks first.
"Silflay hraka, u embleer rah!" Ouch, Woundwort. Ouch.
The movie doesn't really have much humor in it, though Kehaar's "You shtupit bunnies!" rant is a very notable exception.
Don't forget - "Who said that!?" "No-one, sir".
Just picturing Zero Mostel making bird noises in the studio is worth a few laughs. Plus, his declaration of "Perfect landing!" to no one in particular.
Bigwig's take on the prospect of mating:
"Lots of little Bigwigs, Hazel! Think of that and tremble!"
Something similar happens when Hawkbit is excited about having a mate, saying, "Imagine it! Little Hawkbits running all over the place!" Followed by "...what a ghastly thought!"
The whole business about how the Efrafan siege ended. Vervain, one of the most Jerkass rabbits in all of Efrafa, a bully and tyrant almost as bad as Woundwort himself, running away like a little kitten, absolutely terrified of the smallest/physically weakest rabbit in the entire story. And then, the rest of the Efrafans who were caught inside the Watership Warren surrender themselves to the same runt rabbit. Big, bad Efrafans, surrendering to the weakest rabbit around. Dramatic Irony, anyone?
Bluebell's report on the temporary winter burrows:
Hazel: Are the holes hidden?
Bluebell: Just like Efrafa, I should think! In fact I brought one here to show you. You can't see it, can you? Well, there you go!
When the rabbits discover Kehaar, the seagull with an injured wing.