Monkey Island 4 (Escape from Monkey Island) Easter Egg - Engine Swap at the Scumm Bar

Just before leaving Melee Island for the first time, Guybrush recruits three crew members: Otis, Carla, and Ignatius Cheese. He finds Mr. Cheese at the Scumm Bar, but he won't go because he's afraid the bar will fall into Ozzy Mandrill's hands while he's gone. Guybrush convinces him to go. When they get back, the bar has been taken over and is now the Lua Bar.

The significance? Well, the first three Monkey Island games ran on the SCUMM (Script Creation Utility for Maniac Mansion) engine and the bar was named for it in the Secret of Monkey Island. Escape from Monkey Island uses Grim Fandango's LUA engine instead. So that's the reason for the change.