One of the first instances, of course, is Andréa waking up and realizing that Elwood is sleeping right next to him. And that they're naked.
Several minutes later, while wearing nothing but a towel and his shoes, Andréa lectures a guard in front of Orane. What he doesn't realize for a few minutes:
Elwood: Théo! Your towel… it fell down.
Elwood falling down in a large hole while avoiding the one Andréa pointed out to him.
Elwood: Sir, I regret to inform you that I refuse to walk anywhere further.
In a situation of urgency, Andréa uses Elwood's jacket to smother a fire. He then conveniently forgets to tell Elwood how and why it happened.
After the Transparents and ferrets evade a human plane by hiding their dirigible in the clouds, Elwood decides to "knock on wood" to ensure their luck continues. Unable to see in the fog, he promptly bangs his nose on a wooden door.
Father Lizon starts a long tirade about an evil beverage and the "monstrosities" (the hybrids, Yz and Meth) that dwell within. You'd think that he was speaking about sacramental wine…
Father Lizon: Oh God! I give up on water!
When Andréa and Elwood learn from Orane that, in the World of the Oak, just thinking about a mythical creature is enough to wake that creature from the lethargy it's been in for eons.
Elwood: I would then suggest that we forbid your sister from forming even a single thought, Sir. We might risk the apocalypse otherwise.