In "Chapter 3: Lair of the Leviathan", if you actually give Coronado De Cava 100,000 grubs, he will say "Excellent! That's all the grubs we need! We'll be out of here faster than you can say dusky leaf monkey!", and then raise the sunken ship to the surface.
Contributed by KnowledgeBase
The developers originally wanted to include a puzzle in the first episode that took place in Club 41, the bar on Flotsam Island, but had to cut it due to size limitations. Club 41 was named after the 40MB file size limitation of the Wii, making reference to the 41st MB that they couldn't fit into the game.
Contributed by usyboroda
In Episode 5: Rise of the God Pirate, there's a drinks vending machine that players can interact with. One of the drinks available to select is "Grog XD" which is sold out.

This is a reference to an Argentinian TV news report presented by channel C5N, believing it to be a drink kids were consuming, unaware the ingredients were from The Secret of Monkey Island.
Contributed by KnowledgeBase