when i played the original monkey island 3 the interface had a 3d acceleration option. but this never worked. it's only later i realised that this was a joke and the error message reflected that. it was never supposed to be an option.

given how scummvm replaces that section of the game (save/load area) this portion is never replicated in scummvm. which i think is a shame. any other similar situations?

https://youtu.be/iFG4z_UOx2A

Yeah, I noticed the menu as well. Bit of a shame it isn't the original menu but oh well... the game plays perfectly and I still got the original discs.

ScummVM do provide original menu for some games.
But I am not sure if Monkey Island 3 have this ScummVM-only option.