Maniac Mansion (NES version)
The NES version of Maniac Mansion features many cosmetic differences from the original version, mostly because of censorship, but one of them is the music for the arcade game "Meteor Mash", that now includes the first notes of the overworld theme from Super Mario Bros.
To make the game work, the player has to make a charachter fix the wires in the attic, so that the arcade room it's powered, and then use a quarter with the game to make it work. To fix the wires the player needs a character to turn off the circuit breakers in the basement and then another character to use the tools with the wire while having the flashlight turned on with the radio batteries in. The quarter can be found inside the envelope kept in the safe, or in the coin box of the arcade itself after Dr. Fred plays the game, and it can be opened using the small key found in Nurse Edna's room.
The NES version of Maniac Mansion was licensed by Nintendo, so its creators could freely include a small reference to the Mario series.