In the original The Secret of Monkey Island (1990), close-ups of characters in the game were done as 8-bit renderings of pictures of real people. For example, Elaine Marley's appearance was based on Avril Harrison, one of the graphic designers at LucasArts. Creator Ron Gilbert was always bothered with these portraits, as they did not match the cartoonish style of the rest of the game. In the Special Edition, all close-ups have been replaced by original artwork that more closely matches the rest of the game's aesthetics.
In the underground cave where LeChuck's ship is found, one of the faces embedded in the rocks is from Manny Calavera from Grim Fandango (1998), also a LucasArts game.
Among the many idols surrounding the Giant Monkey Head, there is an idol shaped like Purple Tentacle from Day of the Tentacle (1993) (and another one in silhouette in the back), also from LucasArts.