Early in the game, there is a painted woman who is nude, and if you open the curtain hiding her she gets angry and slaps you. In Version 1.04, however, going back there with Garry causes her to slap him instead.
In Version 1.04, returning to the room with the ant while Garry is present leads to the two of them having a really funny argument.
Statues are a great inconvenience in the game. Garry has to constantly push them out of the way and Ib and Mary are simply too small to even attempt such a thing. But then on the "A Painting's Demise" ending path, you wind up playing as Mary, who... politely asks a statue to move out of the way. And it works.
While for the most part Mary's breakdown in the brown area is very upsetting, some of the things that Mary can say during this are quite fun. At one point she asks Ib if she's ever chomped down on a crayon, and declares that it tastes really bad.
In the Bonus Dungeon, Garry and Ib at one point find themselves almost entirely in the dark. Some sort of decoration falls over, causing Garry to scream, and you are given the option of telling him that his screaming is scarier than the thing falling over was.