Mega Man II was finished five months after the first game by a completely different development team that knew very little about the Mega Man series. It shows.

Robot Master Select #2

Set memory address CF66 to 04 - 07 on the Robot Master select screen and you'll be able to choose the Mega Man 3 Robot Masters. Interestingly, they have animations and text strings that aren't used anywhere else in the game. They were clearly meant to be used, but they aren't. After beating the Robot Master, you'll be thrown back to the stage select.

Their stage select icons can be found below.

Unused Music

One track is unused in the game. It seems to be an alternate version of the ending theme.

Unused Level Tiles

Metal Man

The gears in Metal Man's stage are supposed to be animated, like in the NES version. The two gear frames are loaded into memory, but the developers never got the actual animation part of this done.

Hard Man

A rocky platform, clearly modeled after the NES version. The final game's Hard Man level is decidedly industrial in theme, though it may have changed during development.

Magnet Man

More generic foreground and background tiles. The first tile is based on the tiles used in the NES version for the inside sections of Magnet Man's stage. They were replaced by the more eye-pleasing striped tiles. The next two tiles are intended for the outside background, but aren't used. The last tile should have been placed above the magnets (similar tiles appear in the NES version, and there's even space for them in the Game Boy version), but they're not.

Needle Man

Some background and foreground tiles, as well as some spikes. The long vertical background piece (the one with the hole in it) is used in the NES version of Needle Man's stage for the inside sections. The tiles at the bottom are used in the NES version as floor tiles.

Top Man

The NES Top Man stage had spikes, so it would make sense for them to appear in the Game Boy version, but nope. The other two tiles are background tiles that never have a chance to get used. They're completely unique to the Game Boy version, too.

Time Warp

Short and long pipes. Their actual function is unknown. One part of them is actually used in the game, but it's so ill-fitting that it might be a programming error.

Other Unused Graphics

To do: There's more

Unused graphics not related to the actual levels.

Crash Man

Early	Final

A poorly made early walking frame for Crash Man. Luckily, it was replaced with a much better sprite.

Earth

Full	In-Game

The Earth graphic is slightly larger than it appears in-game – 16 pixels are cut off from the bottom.

Font

An unused shaded font. This appears after the font used in the credits, so that's probably where it was meant to be used.

Metal Man

Early	Final

An early, single-framed version of the Metal Blade can be found in Metal Man's sprite set. This 16x16 sprite seems more accurate to the NES version than the final sprite, which uses two 8x8 tiles that are flipped vertically and horizontally for each frame.

Odd Face

Some kind of face thing. This appears in the Air Man stage's object set, possibly being an early version of the Petit Goblin.

Pipi

Early	Final

The hilarious looking early Pipi is part of Wood Man's sprite set. These enemies appear in Wood Man's stage in the NES game, but not in the Game Boy version, so their art was never updated.

Early	Final

The Pipi egg is a dinky 8x8 sprite in the Wood Man sprite set.

Early	Final

The Copipis that hatch from the egg have only one frame of animation in the Wood Man set.

Quint Intro

An unused intro animation for Quint. He just stays still in the final version.

Stage Select Robot Masters

Early	Final

Early versions of the Robot Masters appear in the ROM.

The early Robot Master graphics actually use the background palette. They were probably used in a stage select like the one in Mega Man: Dr. Wily's Revenge.

Wily Shuttle

Unused	Used

A number of different sized images for Dr. Wily's spaceship.

Regional Differences

Top Man's Stage

Japan & US	EU

One block was removed from this sliding tunnel. In the Japanese and American versions Mega Man would reach the end of the tunnel and stop moving but would get stuck in his sliding animation, which looked rather silly.

Needle Man's Stage

Japan & US	EU

The platform at the top of this screen was lengthened to keep the player from jumping on top.

Room Before Final Boss

Japan & US	EU

The platform with a second Scworm generator was removed, replaced with a large background bubble. Orb? Planet? Round thing.

End Credits

Japan & US	EU

The Have "Su" Bee's name was misspelled in earlier revisions.

Oddities

In this area from Crash Man's (or Clash Man, as it appears in the game) stage, no enemies appear when Mega Man enters for the first time, but if he moves forward a little and returns, a Telly enemy will continuously appear. While it was probably added to attack players that run away from the Blocky enemy, it is an unusual feature from the Mega Man series and can be easily missed.