Pretty much anything involving Ferdinand the Duck.
"Christmas Means Carnage!"
And the Rooster who is beaten to the roof by him.
Babe trotting by a stoic Farmer Hoggett at the competition, as the line of text displayed on the television reads "PIG".
A subtle joke, but when Babe is first talking with the sheep at the sheep-dog trial, one of them starts to defecate.
Yep. They were playing up the Dumb Animal routine to the hilt, out of, quite literally, both ends. They didn't think any better of Babe then the crowd did. The Oh Crap look on their faces, though, when Babe recited the Sheep's Creed? Even funnier.
When Ferdinand is fixing to crow for the second time, right before the alarm clock goes off, cutting him off, he quickly goes "mi-mi-mi-mi-mi..." as if to get his pitch right. I don't know why, but it makes me laugh every time.