LegacyRockman 3 marked the appearance of nearly every standard to the Rockman formula: Rush the dog, Rockman's slide, Blues, and the occasional reappearance of old Wily Robots. Just remember though: that's most of the standards. Others like the Teleporter Room (go through eight teleporters and beat all the Wily Robots again) and Rock Buster appeared in Rockman 2 and Rockman 4, respectively.
MusicHarumi Fujita was originally hired to compose the sound for this game, but could only compose the Gemini Man and Magnet Man themes and part of the Staff Roll theme before dropping off the project (and eventually leaving Capcom) to give birth. Her husband Yasuaki was then hired to complete the project. Harumi is credited in Special Thanks as "Mrs. Tarumi".
NES versionIn the original NES version of this game, players could access secrets by plugging in a second controller. For example, if the player holds right on the second controller and presses A on the first controller, Mega Man will do a super jump, and if the player holds right on the second controller when falling into a pit, Mega Man won't lose a life. However, these codes cannot be used in the Rockman Complete Works, Mega Man: The Wily Wars, and Mega Man Anniversary Collection versions. The reasons are unclear, but it is likely that this was because a sort of debug mode was accidentally left in the final NES version.
Information also contributed by Alexander Michel