Well I made this save for anyone who didn't want to get this achievement. Link - http://www.mediafire...3jawr4776zw7q3i Replace ID's then Save, Rehash, Resign. When you load the saved game load up Harley Quinn's Revenge. Once loaded go down the stairs and take a left across the bridge. Turn right then left, The last balloon is near a wooden canoe. Also there's a picture of the location of the last balloon in the folder.