Two from Disneyland Shanghai:
Pirates of the Caribbean: Battle for the Sunken Treasure - realising just why the roof of the building was so tall. Also y'know, that bit after it.
The queueline reveal of the TRON coaster was also super cool.
Elsewhere, we somehow discovered I Corsari in Gardaland...
Yeah, exactly. The theme of ToT is mystery, so the addition of extra elements that only observant people notice fits perfectly within the narrative - and the fact that it's optional lets the person who observes it become part of the story without having to explicitly tell them that.