Resident Evil 4 Limited Edition Pak

To do this, you need at least one normal weapon, and the Infinite Rocket Launcer.

At the begining of each chapter hit an enemy with any weapon once (any weapon other than the IRL) You can then fire away at anything with the Rocket Lancher, no matter if you hit or miss an enemy, and you will get 100% hit rate at the end of the chapter.
This happens because the game does not register the Rocket Launcher hits like the other weapons hits.

After your second encouter with The Village Chief head straight back to the previous room where you met him. A scene will occur where Ada saves you from The Village Cheif again.

After you watch the credits at the end of "Assignment Ada" it will ask you if you would like to watch the credits again. Choose "yes" and it will play the credits again but with different music.