I’ll need a better source than another Trivia website.
As it stands, I was unable to find anything about Pac-Man being in Monster’s Inc, where the Pac-Man Easter egg in Tron is a real thing.
From what I’ve been researching the correct answer is Tron. “During the scene where Tron and Ram escape from the Light Cycle arena into the system, Pac-Man can be seen behind Sark.”
There is no Pac-Man reference in Monsters, Inc.