Just the appearance of Flit, popping out of Camille's throat. It's just so offbeat that it's hilarious.
In "Sigh of the Tiger", after Casey gets fed up with RJ apparently making him do chores while his friends are fighting for their lives, RJ demonstrates how all but one of them will have some use against the monster of the week. Casey, grateful, runs off to join the fight - then remembers there's still one "lesson" and runs back.
Casey: "The back-rub-thing, how does that help me?"
RJ: "Oh, that...doesn't. I just slept funny last night."
After Casey gets ambushed and has his tiger spirit drained of power in "Tigers Fall, Lions Rise", the other Rangers have this to say:
Dom: "I can't believe you got attacked by a Phantom Beast out of nowhere."
Lily: "I can't believe he has a tiger spirit just like yours."