On the short path, the guard dogs Wolf and Bay occasionally swap names (and voices) as well as the dogs Jowls and Mite when confronted by Alexander.
Many items in the pawn shop refer to obstacles from the previous games, among them a bottle of "Gnome-be-gone". However, not gnomes but dwarfs were troublesome in the previous games, while the gnomes were friendly and helpful.
If you put the hole-in-the-wall on the side wall of the Castle of the Crown and peek through it, you see the basement hall with regular doors on the other side. When you enter the castle through the side later on, the dungeon doors are on that same wall.
After Alexander hides behind a pillar from the 2 guard dogs. He hears them talking, then the Narrator informs the player about the woman screaming which Alexander shouts "Cassima!" which would've given Alexander hiding spot away, notified the 2 guard dogs where Alexander is hiding, it would've likely resulted in Alexander getting arrested and thrown in the dungeon and the player would've got a game over message. However the game continues on as normal despite Alexander's accidental yelling as it's possible that Alexander was thinking it in his head and didn't say it out loud knowing the guard dogs would hear.
On the minimum path, when Alexander is in the alcove in the castle hallway, the pillar and the right wall is reflected on the floor, but there is no reflection of Alexander on the floor. Same thing applies for the portrait if it's on the floor.
On the Isle of Wonder you can give the sense gnomes plausible items like the peppermint leaves (for the taste gnome) or the feather (for the touch gnome), but they do not have any effect, and will cause the player to lose.