Bug: Woodman Stage: After defeating the second Friender enemy (the large fire breathing blue cats), if you hang to the right of the screen when jumping down to the next area and are still hanging in the air when the screen scrolls over, MegaMan will phase right through he wall instead of going under it, just before reaching the third Friender.
Trivia: Megaman 1 was actually a failure at launch, and Capcom did not want to make a sequel. However, after pushing from the dev team, they agreed to greenlight Megaman 2, but only if the developers continued to work on their other projects. So they only worked on this game in their spare time and only had 3 to 4 months to finish the game. Then, after it was released, it went on to be the best-selling Megaman game until finally being surpassed by Megaman 11 many years later.