premise: The "Crazy Castle" series is an action-puzzle game series created by Kemco and released on the Famicom Disk System, NES, Game Boy, Game Boy Color and Game Boy Advance. It stars different popular cartoon characters, most notably the Warner Bros. cartoon character, Bugs Bunny, and the Walt Disney cartoon character, Mickey Mouse.
hypothesis: Mickey Mouse and Bugs Bunny are not the only cartoon characters to appear in the series.
reason: The passage says that "different popular cartoon characters" cartoons appear in the series and mentions Bugs Bunny and Mickey Mouse with the qualifier "most notably". This means that other cartoon character must have been in the series. I'm guessing the system was confused because no other specific characters are mentioned at all.